Substrate polishing apparatus

ABSTRACT

A substrate polishing apparatus is used to polish a surface of a substrate such as a semiconductor wafer to a flat mirror finish. The substrate polishing apparatus has a polishing table and a polishing pad mounted on the polishing table for polishing a semiconductor substrate. The polishing pad has a through hole formed therein. The substrate polishing apparatus also has a light emission and reception device for emitting measurement light through the through hole formed in the polishing pad to the semiconductor substrate and receiving reflected light from the semiconductor substrate so as to measure a film on the semiconductor substrate. The light emission and reception device is disposed in the polishing table. The substrate polishing apparatus includes a supply passage for supplying a fluid to a path of the measurement light. The supply passage has an outlet portion detachably mounted on the polishing table. The substrate polishing apparatus also includes a protection cover mounted on the polishing table and fitted into the through hole when the polishing pad is attached to the polishing table.

This application is a divisional application of U.S. application Ser.No. 11/274,112, filed Nov. 16, 2005, which is a continuation-in-part ofU.S. application Ser. No. 10/617,794 filed Jul. 14, 2003 andinternational application No. PCT/JP2004/006768 filed May 13, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate polishing apparatus, andmore particularly to a substrate polishing apparatus capable ofimproving measurement accuracy of a substrate measuring device which isincorporated in the substrate polishing apparatus.

2. Description of the Related Art

In a semiconductor fabrication process, a substrate polishing apparatusis used to polish a surface of a substrate such as a semiconductor waferto a flat and mirror surface. The substrate polishing apparatus has arotatable table (polishing table), and a substrate is pressed against apolishing surface on the rotatable table. Then, while a polishingabrasive is supplied onto the polishing surface, the rotatable table isrotated to polish the substrate. There has been proposed a substratemeasuring device utilizing light as a device for measuring a film on asubstrate during polishing the substrate. For example, a film thicknesscan be measured to determine an end point of polishing based on themeasured film thickness.

There has been proposed a stream-type device as this type of substratemeasuring device. For example, Japanese laid-open patent publication No.2001-235311 discloses a substrate measuring device having a water supplypassage provided in a rotatable table. An outlet of the water supplypassage is provided in the polishing surface, and pure water is ejectedthrough the water supply passage to the substrate. Two optical fibersare disposed in a stream. Measurement light is emitted through one ofthe optical fibers to the substrate, and reflected light is receivedthrough the other of the optical fibers from the substrate. Then, thefilm thickness is calculated based on the reflected light.

In the above substrate polishing apparatus, the substrate is polished inthe presence of the polishing abrasive between the substrate and thepolishing surface. When the polishing abrasive flows into the pure watersupplied through the water supply passage, the transparency of the purewater is lowered. As a result, an amount of the reflected light that hasbeen received is lowered. Therefore, it has been a task for thestream-type measuring device to prevent the pure water from being mixedwith the polishing abrasive or keep the transparency of the pure waterto such a degree that the measurement is not affected even when thepolishing abrasive flows into the pure water.

The above substrate polishing apparatus has several expendablecomponents. One of the expendable components is a light source componentfor emitting measurement light. The light source component comprises alamp, for example. The lamp has a service life of about four months, forexample, although the service life varies depending on the type of lampand condition under which the lamp is used. The substrate polishingapparatus may have a control valve disposed in the water supply passagefor controlling water-injection timing. In this case, the control valvemay be one of the expendable components.

The expendable components are usually embedded in the polishing table.For example, the expendable components are disposed inwardly of a skirtwhich is provided along an outer edge of the polishing table.

The expendable components are required to be replaced at regular orirregular intervals. In a replacing operation, an operator puts a handinto the skirt of the polishing table from below the skirt, and thenreplaces the expendable components. However, it is difficult for theoperator to reach the expendable components, and hence the replacingoperation is not easy to accomplish.

The stream-type substrate measuring device described above supplieswater into a through-hole formed in a polishing pad, so that slurryflowing between the polishing table and the substrate into thethrough-hole can be diluted, and that the slurry attached to thesubstrate can be cleaned. Thus, influence on measurement from the slurryis reduced to maintain a required capability of measurement.

However, a large amount of water should be supplied in order to maintaina required capability of measurement. When a large amount of water issupplied, the water flows to the polishing surface on the polishingtable to cause the slurry to be diluted. Dilution of the slurry may havean influence on the characteristics of the polishing capability.Heretofore, as described above, if the amount of water is increased inconsideration of the measuring capability, the polishing capability islowered, and there is a trade-off relationship between the measuringcapability and the polishing capability.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above drawbacks. Itis an object of the present invention to provide a substrate polishingapparatus which can reduce the influence that a polishing abrasive hason film measurement, and allows an expendable component to be replacedeasily, and can reduce the influence that a measurement fluid has on thepolishing capability while maintaining the measuring capability of asubstrate measuring device.

In order to achieve the above object, according to a first aspect of thepresent invention, there is provided a substrate polishing apparatuscomprising: a polishing table; a polishing pad mounted on the polishingtable for polishing a semiconductor substrate, the polishing pad havinga through hole formed therein; a light emission and reception device foremitting measurement light through the through hole formed in thepolishing pad to the semiconductor substrate and receiving reflectedlight from the semiconductor substrate so as to measure a film on thesemiconductor substrate, the light emission and reception device beingdisposed in the polishing table; a supply passage for supplying a fluidto a path of the measurement light, the supply passage having an outletportion detachably mounted on the polishing table; and a protectioncover mounted on the polishing table and fitted into the through holewhen the polishing pad is attached to the polishing table.

According to a second aspect of the present invention, there is provideda polishing apparatus comprising: a polishing table having a polishingpad for polishing a workpiece, said polishing pad having a hole; anoptical measurement device disposed in said polishing table for emittingmeasurement light to the workpiece through said hole and receivingreflected light from the workpiece so as to measure a film on theworkpiece; a supply passage disposed in said polishing table forsupplying a fluid to a path of the measurement light, said supplypassage having an outlet portion detachably mounted on said polishingtable; and a protection cover mounted on said polishing table and fittedinto said hole when said polishing pad is attached to said polishingtable.

According to a second aspect of the present invention, there is provideda polishing apparatus comprising: a polishing table having a polishingpad for polishing a workpiece, the polishing pad having a hole; anoptical measurement device disposed in the polishing table for emittingmeasurement light to the workpiece through the hole and receivingreflected light from the workpiece so as to measure a film on theworkpiece; a supply passage disposed in the polishing table forsupplying a fluid to a path of the measurement light, the supply passagehaving an outlet portion detachably mounted on the polishing table; anda protection cover mounted on the polishing table and fitted into thehole when said polishing pad is attached to the polishing table.

According to the present invention, since the outlet portion of thesupply passage is positioned in the through hole, the outlet portion ofthe supply passage is close to the semiconductor substrate. Therefore, aflow velocity of the fluid supplied from the supply passage is increasedat the outlet portion, and the fluid is vigorously ejected from a gapbetween the semiconductor substrate and the outlet portion toward theoutside of the supply passage, thus forming a flow of the fluid alongthe semiconductor substrate. The flow of the fluid can effectivelyremove a polishing abrasive from an area where the measurement light isapplied, which is located in front of the outlet portion.

In a preferred aspect of the present invention, the outlet portion isdetachably mounted on the rotatable table.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a rotatable table having apolishing pad for polishing a semiconductor substrate; a light emissionand reception device for emitting measurement light through a throughhole formed in the polishing pad to the semiconductor substrate andreceiving reflected light from the semiconductor substrate so as tomeasure a film on the semiconductor substrate; and a supply passage forsupplying a fluid to a path of the measurement light; wherein the supplypassage has an outlet portion detachably mounted on the rotatable table.

With this structure, the outlet portion can be mounted after thepolishing pad is installed on the rotatable table. Therefore, thepolishing pad can be easily installed in position. The outlet portioncan be removed before the polishing pad is removed. Thus, the polishingpad can be easily removed without causing damage to the outlet portion.The outlet portion projects from the rotatable table closely to thesubstrate. Consequently, a flow velocity of the fluid supplied from thesupply passage is increased at the outlet portion, and the fluid isvigorously ejected from a gap between the semiconductor substrate andthe outlet portion toward the outside of the supply passage, thusforming a flow of the fluid along the semiconductor substrate. The flowof the fluid can effectively remove a polishing abrasive from an areawhere the measurement light is applied, which is located in front of theoutlet portion.

In a preferred aspect of the present invention, the light emission andreception device is mounted on the outlet portion.

With this structure, the light emission and reception device can bedisposed in the through hole and can be thus positioned closely to thesemiconductor substrate. Therefore, the reflected light can be receivedefficiently. Since the light emission and reception device and theoutlet portion can be installed and removed together with each other,the light emission and reception device does not obstruct when replacingthe polishing pad.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a rotatable table having apolishing pad for polishing a semiconductor substrate; a light emissionand reception device for emitting measurement light through a throughhole formed in the polishing pad to the semiconductor substrate andreceiving reflected light from the semiconductor substrate so as tomeasure a film on the semiconductor substrate; a supply passage forsupplying a fluid to a path of the measurement light; and an outletportion moving means for moving an outlet portion of the supply passagealong a direction in which the through hole extends.

With this structure, the outlet portion can be moved into the throughhole after the polishing pad is installed on the rotatable table.Further, the outlet portion can be moved and accommodated in therotatable table before the polishing pad is removed. Therefore, thepolishing pad can be easily replaced without causing damage to theoutlet portion. The outlet portion projects from the rotatable table toa position closely to the substrate. Consequently, a flow velocity ofthe fluid supplied from the supply passage is increased at the outletportion, and the fluid is vigorously ejected from a gap between thesemiconductor substrate and the outlet portion toward the outside of thesupply passage, thus forming a flow of the fluid along the semiconductorsubstrate. The flow of the fluid can effectively remove a polishingabrasive from an area where the measurement light is applied, which islocated in front of the outlet portion.

In a preferred aspect of the present invention, the outlet portionmoving means moves the light emission and reception device together withthe outlet portion.

With this structure, the light emission and reception device can bedisposed in the through hole and can be thus positioned closely to thesemiconductor substrate. Therefore, the reflected light can be receivedeffectively. Since the light emission and reception device and theoutlet portion can be installed and removed together with each other,the light emission and reception device can be moved and accommodated inthe rotatable table when replacing the polishing pad. Therefore, thelight emission and reception device does not obstruct when replacing thepolishing pad.

In a preferred aspect of the present invention, the outlet portionmoving means comprises an urging means for urging the outlet portiontoward a polishing surface of the polishing pad, and a limiting meansfor limiting movement of the outlet portion caused by the urging means,so that the outlet portion does not project from the polishing surface.

According to the present invention, the outlet portion is urged by theurging means to move toward the polishing surface, so that the outletportion is disposed in the through hole. The outlet portion can be movedtoward the rotatable table against the urging force of the urging means.When replacing the polishing pad, if the polishing pad is placed ontothe outlet portion, the outlet portion is pressed by the polishing padand accommodated in the rotatable table. When the through hole of thepolishing pad and the outlet portion are aligned with each other, theoutlet portion is urged to project into the through hole. Therefore, theoutlet portion does not obstruct the installation of the polishing pad,and hence the polishing pad can be easily positioned.

In a preferred aspect of the present invention, the outlet portionmoving means adjusts the position of the outlet portion according to adressing process of the polishing surface of the polishing pad.

According to the present invention, the position of the outlet portionis adjusted according to a thickness of the polishing pad that has beenscraped by the dressing process. Therefore, the substrate and the outletportion can be kept in a suitable positional relationship.

In a preferred aspect of the present invention, a substrate polishingapparatus comprises a rotatable table having a polishing pad forpolishing a semiconductor substrate; a light emission and receptiondevice for emitting measurement light through a through hole formed inthe polishing pad to the semiconductor substrate and receiving reflectedlight from the semiconductor substrate so as to measure a film on thesemiconductor substrate; a supply passage for supplying a fluid to apath of the measurement light; and a light emission and reception devicemoving means for moving the light emission and reception device in adirection in which the through hole extends.

With this structure, the light emission and reception device can bedisposed in the through hole and can be thus positioned closely to thesemiconductor substrate. Therefore, the reflected light can be receivedeffectively. Since the light emission and reception device is movable,the light emission and reception device can be accommodated in therotatable table when replacing the polishing pad, and does not obstructthe replacement of the polishing pad.

In a preferred aspect of the present invention, the light emission andreception device moving means adjusts the position of the light emissionand reception device according to the dressing process of the polishingsurface of the polishing pad.

According to the present invention, the position of the light emissionand reception device is adjusted according to the thickness of thepolishing pad that has been scraped by the dressing process. Therefore,the substrate and the light emission and reception device can be kept ina suitable positional relationship, so that the reflected light can bereceived efficiently.

In a preferred aspect of the present invention, a substrate polishingapparatus comprises a rotatable table having a polishing pad forpolishing a semiconductor substrate, a light emission and receptiondevice for emitting measurement light through a through hole formed inthe polishing pad to the semiconductor substrate and receiving reflectedlight from the semiconductor substrate so as to measure a film on thesemiconductor substrate, and a supply passage for supplying a fluid to apath of the measurement light, wherein the supply passage has an outletportion made of a soft material whose softness is substantially the sameas or higher than that of the polishing pad. The outlet portion of thesupply passage may be made of the same material as the polishing pad.

With this structure, the semiconductor substrate is prevented from beingdamaged when the outlet portion is brought into contact with thesemiconductor substrate while the semiconductor substrate is polished.Therefore, the outlet portion can be positioned closer to thesemiconductor substrate, and an outlet can be positioned substantiallyin the same plane as the polishing surface. According to the presentinvention, the outlet portion and the polishing pad can be dressedtogether, and hence the outlet portion can be adjusted in verticalposition together with the polishing pad for thereby allowing the outletto be easily positioned substantially in the same plane as the polishingsurface.

In a preferred aspect of the present invention, a substrate polishingapparatus comprises a rotatable table having a polishing pad forpolishing a semiconductor substrate, a light emission and receptiondevice for emitting measurement light through a through hole formed inthe polishing pad to the semiconductor substrate and receiving reflectedlight from the semiconductor substrate so as to measure a film on thesemiconductor substrate, and a supply passage for supplying a fluid to apath of the measurement light, wherein the supply passage has an outletportion made of a material having a larger elastic modulus than that ofthe polishing pad.

With this structure, the vertical position of the outlet portion can beadjusted by setting a dressing pressure higher than a polishing pressureas described below. Specifically, first, the substrate polishingapparatus dresses the outlet portion together with the polishing pad.Since the elastic modulus of the outlet portion is larger than theelastic modulus of the polishing pad, when the dressing process isfinished and the pressure applied during the dressing process isreleased, the polishing pad extends such that the expansion of thepolishing pad is greater than that of the outlet portion. Therefore,when the dressing process is finished, the outlet portion is retractedinto the through hole of the polishing pad. In the substrate polishingapparatus, the polishing pressure is set to be smaller than the dressingpressure. Consequently, when the substrate is polished, the outletportion does not project from the polishing surface and thus remainspositioned in the through hole of the polishing pad without interferingwith the polishing process.

In a preferred aspect of the present invention, a substrate polishingapparatus comprises a rotatable table having a polishing pad forpolishing a semiconductor substrate, a light emission and receptiondevice for emitting measurement light through a through hole formed inthe polishing pad to the semiconductor substrate and receiving reflectedlight from the semiconductor substrate so as to measure a film on thesemiconductor substrate, and a supply passage for supplying a fluid to apath of the measurement light, wherein the supply passage has a mirrorinner surface.

According to the present invention, since the supply passage has themirror inner surface, absorption of light in the supply passage issuppressed to reduce the attenuation of the measurement light and thereflected light. Accordingly, the amount of the reflected light to bereceived is increased, resulting in an increase in S/N ratio.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a rotatable table having apolishing pad for polishing a semiconductor substrate; a light emissionand reception device for emitting measurement light through a throughhole formed in the polishing pad to the semiconductor substrate andreceiving reflected light from the semiconductor substrate so as tomeasure a film on the semiconductor substrate; and a supply passage forsupplying a fluid to a path of the measurement light; wherein the supplypassage has a nonreflective inner surface.

According to the present invention, the nonreflective inner surface iseffective to suppress the reflection of light in the supply passage,thus reducing wavelength shift due to the reflection on the innersurface of the supply passage. Accordingly, in the case where the filmon the substrate is measured based on the wavelength shift, thenonreflective inner surface is capable of increasing S/N ratio.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a rotatable table having apolishing pad for polishing a semiconductor substrate; a light emissionand reception device for emitting measurement light through a throughhole formed in the polishing pad to the semiconductor substrate andreceiving reflected light from the semiconductor substrate so as tomeasure a film on the semiconductor substrate; a supply passage forsupplying a fluid to a path of the measurement light; and a protectioncover detachably mounted on the rotatable table when the polishing padis replaced; wherein the protection cover is received in a through holeformed in the polishing pad and covers an opening which constitutes thesupply passage formed in the rotatable table.

According to the present invention, since the protection cover isreceived in the through hole of the polishing pad, the polishing pad canbe replaced together with the protection cover attached thereto. Sincethe protection cover covers the opening constituting the supply passage,even if the outlet portion of the supply passage and the light emissionand reception device project from a mount surface of the polishing pad,the polishing pad can be replaced while the supply passage is protectedby the protection cover.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a rotatable table having apolishing pad for polishing a semiconductor substrate; a light emissionand reception device for emitting measurement light through a throughhole formed in the polishing pad to the semiconductor substrate andreceiving reflected light from the semiconductor substrate so as tomeasure a film on the semiconductor substrate; a supply passage forsupplying a fluid to a path of the measurement light; and an auxiliarysupply passage for supplying a fluid positioned at the forward of thesupply passage in a rotating direction of the rotatable table.

According to the present invention, as described below, a transparencyof the fluid in a measuring path can be increased. Specifically, as therotatable table is rotated, the rotatable table and the polishingabrasive are moved relative to each other. As seen from the rotatabletable, the polishing abrasive is moved backward in the rotatingdirection of the rotatable table. According to the present invention,since the auxiliary supply passage is disposed at the forward of thesupply passage in the rotating direction of the rotatable table, thepolishing abrasive is diluted in a location forward of the measuringarea. Specifically, the polishing abrasive is primarily diluted in theauxiliary supply passage, and then secondarily diluted in the rearmeasuring area. Thus, the transparency of the measuring area isincreased, and hence the measurement accuracy can be increased.

In a preferred aspect of the present invention, the auxiliary supplypassage has an outlet disposed in the through hole.

With this structure, since the outlet of the auxiliary supply passage ispositioned closely to the semiconductor substrate, the polishingabrasive is effectively removed by the fluid supplied from the auxiliarysupply passage. Therefore, the transparency of the measuring area isfurther increased. In the case where the auxiliary supply passage isused, the total amount of the measurement fluid to be supplied (the sumof a main amount of supply and an auxiliary amount of supply) can besmall compare to the case where the auxiliary supply passage is notused. Thus, the consumed amount of the measurement fluid can be reduced.

In a preferred aspect of the present invention, the auxiliary supplypassage has a shape surrounding the supply passage.

With this structure, the supply of the fluid from the auxiliary supplypassage can effectively increase the transparency of the measuring area.

In a preferred aspect of the present invention, the outlet of theauxiliary supply passage is narrower than the outlet of the supplypassage.

With this structure, a flow velocity of the fluid from the precedingauxiliary supply passage is larger than a flow velocity of the fluidfrom the supply passage, and hence the auxiliary supply passage has agreater share in primary diluting of the fluid for thereby furtherincreasing the transparency of the measuring area.

In a preferred aspect of the present invention, a second through holeformed in the polishing pad is supplied with the fluid.

In a preferred aspect of the present invention, a substrate polishingapparatus comprises a rotatable table having a polishing pad forpolishing a semiconductor substrate, a light emission and receptiondevice for emitting measurement light through a through hole formed inthe polishing pad to the semiconductor substrate and receiving reflectedlight from the semiconductor substrate so as to measure a film on thesemiconductor substrate, and a supply passage for supplying a fluid to apath of the measurement light, wherein the supply passage has an outletwhose area is smaller than an area of the other portion of the supplypassage.

With this structure, the flow velocity of the fluid ejected from theoutlet of the supply passage is increased, and hence the influence thatthe polishing abrasive has on measurement can be reduced.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a rotatable table having apolishing pad for polishing a semiconductor substrate; a light emissionand reception device for emitting measurement light through a throughhole formed in the polishing pad to the semiconductor substrate andreceiving reflected light from the semiconductor substrate so as tomeasure a film on the semiconductor substrate; a supply passage forsupplying a fluid to a path of the measurement light; and a polishingpad piece fitted in an opening formed in the polishing pad, the throughhole being formed in the polishing pad piece; wherein the polishing padpiece has a pad piece surface continuously connected to a surface of thepolishing pad, and the pad piece surface is flat.

According to the present invention, the amount of the polishing abrasiveflowing into the through hole can be reduced as follows. Generally, thepolishing pad has a groove serving as a passage for the polishingabrasive and scraped particles in order to wash out the polishingabrasive and the scraped particles smoothly from the polishing surface.The groove may be a path through which the polishing abrasive flows intothe through hole provided for measuring the film. The polishing surfaceof the polishing pad may have a number of dimples. These dimples arealso responsible for increasing the amount of the polishing abrasiveflowing into the through hole. According to the present invention, sincethe polishing pad piece having the through hole has the flat surface,the amount of the polishing abrasive flowing into the through hole canbe reduced. The polishing pad piece is provided separately from thepolishing pad. Therefore, a structure in which the polishing pad has aflat portion can be easily achieved.

In a preferred aspect of the present invention, the polishing pad pieceis made of the same material as the polishing pad.

With this structure, the semiconductor substrate is prevented from beingdamaged while the semiconductor substrate is polished.

In a preferred aspect of the present invention, the substrate polishingapparatus has a fixing means for fixing the polishing pad piece to therotatable table and positioning the polishing pad piece in a positionwhere the measurement light passes through the through hole.

According to the present invention, the polishing pad piece ispositioned and fixed by the fixing means to locate the through hole in asuitable position when the polishing pad is replaced. The polishing padis mounted on the rotatable table so as to be fitted in the opening.Therefore, the through hole can be easily disposed in a suitableposition when the polishing pad is assembled. In the actual apparatus,the size of the through hole for measurement is much smaller than thesize of the polishing pad. Therefore, it is not easy to perform a fineadjustment of the position of the through hole by moving the entirepolishing pad. According to the present invention, the separatepolishing pad piece is provided to eliminate the above adjustingoperation for thereby allowing the assembling operation of the polishingpad to be greatly facilitated. According to the present invention, it ispossible to mount the polishing pad and then mount the polishing padpiece. The polishing pad piece may be installed on a base member, andthe polishing pad piece and the base member may constitute a replacementcartridge. In this case, the replacement cartridge serves as a fixingmeans for fixing the polishing pad piece. Preferably, the replacementcartridge has supply and discharge ports for a measurement fluid, andalso has an emission member for emitting measurement light and areception member for receiving reflected light. This structure allowsthe assembling operation of the measuring device onto the rotatabletable to be facilitated.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a rotatable table having apolishing pad for polishing a semiconductor substrate; a light emissionand reception device for emitting measurement light through a throughhole formed in the polishing pad to the semiconductor substrate andreceiving reflected light from the semiconductor substrate so as tomeasure a film on the semiconductor substrate; and a supply passage forsupplying a fluid to a path of the measurement light; wherein thethrough hole has a water repellent inner surface.

Since the through hole has the water repellent inner surface, ameasurement fluid supplied to the through hole can hardly seep into thepolishing pad. This structure is effective to suppress property changeof the polishing pad due to the fluid which is contained in thepolishing pad, thereby reducing change in polishing characteristics ofthe polishing pad.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a polishing table againstwhich a substrate is pressed; a substrate measuring device disposed inthe polishing table for detecting a film thickness or a polishing endpoint of the substrate; and an expendable component replacement doorwhich is openably and closably disposed on the polishing table forallowing an expendable component to be taken into and out of thepolishing table.

In a preferred aspect of the present invention, the substrate measuringdevice applies measurement light to the substrate and measures a film onthe substrate based on reflected light from the substrate.

According to the present invention, since an expendable component can betaken into and out of the polishing table using the expendable componentreplacement door, the expendable component can be easily replaced.

In the present invention, the expendable component replacement doorincludes an arrangement capable of opening and closing a replacementmouth formed in the polishing table. The expendable componentreplacement door may be attached to the polishing table by a hinge. Theexpendable component replacement door may be slidably provided on thepolishing table. Alternatively, the expendable component replacementdoor may be a removable cover.

In the present invention, the substrate and the polishing table may berelatively pressed against each other. Typically, the substrate is urgedtoward the polishing table. However, the present invention is notlimited to such a structure.

In a preferred aspect of the present invention, the expendable componentcomprises a light source component for emitting the measurement light.The light source component may be a lamp, and the lamp may be a halogenlamp or a xenon flash lamp. Alternatively, the light source componentmay be an LED or a laser light source.

In a preferred aspect of the present invention, the expendable componentcomprises a control valve disposed in a passage for a fluid which isused in a measurement process using the measurement light. The controlvalve may be disposed in a fluid supply passage or a fluid dischargepassage.

In a preferred aspect of the present invention, the expendable componentreplacement door is disposed on a side surface of the polishing table.The operator can easily replace an expendable component through the sidesurface of the polishing table.

In a preferred aspect of the present invention, the expendable componentreplacement door is disposed on a surface of the polishing table againstwhich the substrate is pressed, and is deviated from an orbit of thesubstrate. The expendable component replacement door can be thusdisposed without affecting the polishing process. If the substrate ispositioned upwardly of the polishing table, then the surface of thepolishing table against which the substrate is pressed is an uppersurface of the polishing table. Generally, the polishing pad or a fixedabrasive comprising abrasive particles of cerium oxide (CeO₂) or thelike fixed together by a binder such as resin is mounted on thepolishing table.

The expendable component replacement door may be disposed below thepolishing pad.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a polishing table againstwhich a substrate is pressed; a substrate measuring device disposed inthe polishing table for detecting a film thickness or a polishing endpoint of the substrate; a plurality of expendable components having thesame function, the plurality of expendable components being mounted onthe polishing table and constituting the substrate measuring device; andan expendable component switching means for switching expendablecomponent, of the plurality of expendable components, which functions tomeasure a film on the substrate.

In a preferred aspect of the present invention, the substrate measuringdevice applies measurement light to the substrate and measures a film onthe substrate based on reflected light from the substrate.

According to the present invention, since the expendable components areswitched, the number of times the expendable components are replaced canbe reduced.

According to the present invention, there is also an advantage in thatwhen the expendable component is consumed or breaks down, it is notnecessary to shut off the substrate polishing apparatus immediately toperform a replacing operation. The expendable component may be replacedduring other maintenance operation such as replacing the polishing pad.Therefore, an operating rate of the substrate polishing apparatus can beincreased.

In a preferred aspect of the present invention, the expendable componentswitching means automatically switches the expendable components basedon a usage situation of each of the expendable components which functionto measure the film on the substrate. For example, the expendablecomponent switching means is automatically operated based on a usageperiod in which the expendable component has been used.

According to the present invention, since the expendable components areautomatically switched, the burden on the operator is further reduced.

In a preferred aspect of the present invention, the expendable componentcomprises a light source component for emitting the measurement light ora control valve disposed in a passage for fluid which is used in ameasurement process using the measurement light. The present aspect maybe combined with the ninth aspect described above. In this case, anexpendable component replacement door is provided, and a plurality ofexpendable components having the same function are provided andswitched.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a polishing table againstwhich a substrate is pressed; a substrate measuring device disposed inthe polishing table for detecting a film thickness or a polishing endpoint of the substrate; and an expendable component constituting thesubstrate measuring device and disposed outside of the polishing table.

In a preferred aspect of the present invention, the substrate measuringdevice applies measurement light to the substrate and measures a film onthe substrate based on reflected light from the substrate.

According to the present invention, since the expendable component isdisposed outside of the polishing table, the expendable component can beeasily replaced.

In a preferred aspect of the present invention, the expendable componentcomprises a light source component for emitting the measurement light.

In a preferred aspect of the present invention, the substrate polishingapparatus has the following structure for transmitting light between thepolishing table which is being rotated and the outside of the polishingtable: The substrate polishing apparatus has a fixed-side light guidedisposed outside of the polishing table for transmitting the measurementlight emitted by the light source component to the polishing table; anda rotary-side light guide disposed in the polishing table for receivingthe measurement light from the fixed-side light guide. With thisstructure, the film on the substrate on the rotatable table can bemeasured using the measurement light that is emitted by the light sourcecomponent which is disposed outside of the polishing table.

In a preferred aspect of the present invention, the fixed-side lightguide and the rotary-side light guide have a fixed-side light guide endportion and a rotary-side light guide end portion, respectively, whichface each other when the polishing table is in a predetermined lightguiding region extending in a rotating direction of the polishing table.The substrate polishing apparatus according to the present invention isarranged such that the fixed-side light guide end portion and therotary-side light guide end portion face each other when the polishingtable is in the predetermined light guiding region. Since the endportions of the rotary-side and fixed-side light guides are not requiredto communicate with each other at all times, the structure fortransmitting the light becomes simple. The predetermined light guidingregion is preferably set to include an angular position of the polishingtable where the substrate is in a measurement position. The light istransmitted from the light source component to the polishing table whenrequired for measurement. Consequently, the film can be measuredreliably.

In a preferred aspect of the present invention, the expendable componentcomprises a control valve disposed in a passage for a fluid which isused in a measurement process using the measurement light.

In a preferred aspect of the present invention, the substrate polishingapparatus has the following structure for delivering a fluid between thepolishing table which is being rotated and the fixed side. The substratepolishing apparatus has a fixed-side passage disposed outside of thepolishing table, the control valve being disposed in the fixed-sidepassage; and a rotary-side passage disposed in the polishing table;wherein the fixed-side passage and the rotary-side passage have afixed-side passage end portion and a rotary-side passage end portion,respectively, which face each other when the polishing table is in apredetermined conduction region extending in a rotating direction of thepolishing table. The fixed-side passage and the rotary-side passage maybe a supply passage or a discharge passage.

As described above, the substrate polishing apparatus according to thepresent invention is arranged such that the fixed-side passage endportion and the rotary-side passage end portion face each other when thepolishing table is in the predetermined conduction region extending inthe rotating direction of the polishing table. Since the above endportions are not required to communicate with each other at all times,the structure for delivering the fluid becomes simple. The predeterminedconduction region is preferably set to include an angular position ofthe polishing table where the substrate is in the measurement position.The fluid is delivered to the polishing table when required formeasurement. Consequently, the film can be measured reliably.

In a preferred aspect of the present invention, the substrate polishingapparatus has an orifice forming member having an orifice formingsurface disposed closely to the polishing table with an orifice gapformed therebetween. The orifice forming surface is disposed at aposition corresponding to a position of the rotary-side passage endportion and is disposed in a region where the fixed-side passage endportion is not provided.

According to the present invention, when the rotary-side passage endportion and the fixed-side passage end portion do not face each other,these passage end portions communicate with each other through theorifice gap. Therefore, when the above passage end portions do not faceeach other, the fluid can be delivered at a low flow rate.

In a preferred aspect of the present invention, a substrate polishingapparatus comprises a polishing table against which a substrate ispressed, a substrate measuring device for emitting measurement lightfrom the polishing table to the substrate so as to measure a film on thesubstrate based on reflected light from the substrate, a rotary-sidepassage disposed in the polishing table for passing therethrough a fluidused in a measuring process using the measurement light, and afixed-side passage disposed outside of the polishing table, wherein therotary-side passage and the fixed-side passage have a rotary-sidepassage end portion and a fixed-side passage end portion, respectively,which face each other when the polishing table is in a predeterminedconduction region extending in a rotating direction of the polishingtable. The above passages may be a supply passage or a dischargepassage.

In a preferred aspect of the present invention, the rotary-side passageend portion and the fixed-side passage end portion face each other whenthe angular position of the polishing table is in the conduction region.With this structure, the delivering of the fluid can be controlled, andhence it is possible to dispense with control valves to be provided inthe above passages. Even in the case where such control valves areprovided, the number of times the control valves are operated is greatlyreduced. Therefore, the control valves are not required to be replaced,or intervals for replacing the control valves can be increased.

In a preferred aspect of the present invention, the substrate polishingapparatus has an orifice forming member having an orifice formingsurface disposed closely to the polishing table with an orifice gapformed therebetween. The orifice forming surface is disposed at aposition corresponding to a position of the rotary-side passage endportion and is disposed in a region where the fixed-side passage endportion is not provided.

According to the present invention, when the rotary-side passage endportion and the fixed-side passage end portion do not face each other,these passage end portions communicate with each other through theorifice gap. Therefore, when the passage end portions do not face eachother, the fluid can be delivered at a low flow rate. According to thepresent invention, therefore, small and large flow rates can be switchedby a simple structure of a passage junction.

In a preferred aspect of the present invention, a substrate polishingapparatus comprises a polishing table against which a substrate ispressed, a substrate measuring device for emitting measurement lightfrom the polishing table to the substrate so as to measure a film on thesubstrate based on reflected light from the substrate, a fixed-sidelight guide disposed outside of the polishing table, and a rotary-sidelight guide disposed in the polishing table, wherein the fixed-sidelight guide and the rotary-side light guide have a fixed-side lightguide end portion and a rotary-side light guide end portion,respectively, which face each other when the polishing table is in apredetermined light guiding region extending in a rotating direction ofthe polishing table. In this arrangement, the fixed-side light guide andthe rotary-side light guide are not limited to light guides formeasurement light, but may be light guides for reflected light.According to the present invention, the structure for transmitting lightbetween the rotary side and the fixed side can be simplified.

In a preferred aspect of the present invention, a substrate polishingapparatus comprises a polishing table against which a substrate ispressed, a rotary-side passage disposed in the polishing table forpassing a fluid therethrough, and a fixed-side passage disposed outsideof the polishing table, wherein the rotary-side passage and thefixed-side passage have a rotary-side passage end portion and afixed-side passage end portion, respectively, which face each other whenthe polishing table is in a predetermined conduction region extending ina rotating direction of the polishing table. According to the presentinvention, the flow of the fluid can be controlled by a simple structurefor delivering the fluid between the rotary side and the fixed side. Inthis arrangement, the fluid to be delivered is not limited to ameasurement fluid. The fluid may be delivered from the fixed side to therotary side or vice versa.

In a preferred aspect of the present invention, a substrate polishingapparatus comprises a polishing table against which a substrate ispressed, a rotary-side light guide disposed in the polishing table forpassing light therethrough, and a fixed-side light guide disposedoutside of the polishing table, wherein the rotary-side light guide andthe fixed-side light guide have a rotary-side light guide end portionand a fixed-side light guide end portion, respectively, which face eachother when the polishing table is in a predetermined conduction regionextending in a rotating direction of the polishing table. According tothe present invention, the timing of transmission of light can becontrolled by a simple structure for transmitting the light. In thisarrangement, the light to be transmitted is not limited to measurementlight. The light may be transmitted from the fixed side to the rotaryside or vice versa. While various aspects of the present invention havebeen described above, the present invention is not limited to the abovesubstrate polishing apparatuses. For example, another aspect of thepresent invention includes a substrate measuring device incorporated inthe above substrate polishing apparatus.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a polishing table againstwhich a substrate is pressed; a light emission and reception device foremitting measurement light from the polishing table to the substrate andreceiving reflected light from the substrate so as to measure a film onthe substrate; and a fluid supply device for supplying a measurementfluid, which transmits the measurement light and the reflected light, toan area where the measurement light is applied; wherein the fluid supplydevice supplies a solvent used in a polishing slurry as the measurementfluid. The solvent is defined as a non-polishing-abrasive ingredient ofthe slurry. The substrate and the polishing table are relatively pressedagainst each other.

Typically, the substrate is urged toward the polishing table. However,the present invention is not limited to such a structure.

According to the present invention, since the solvent of the slurry issupplied as a measurement fluid, even if the measurement fluid flows outonto the polishing table and is mixed with the slurry, the influencethat the diluted slurry has on the polishing capability can be reduced.The present invention is based on the fact that even if the slurryitself has a low transparency, the transparency of the slurry solvent isrelatively high. Therefore, the measuring capability is maintained byusing the solvent of the slurry, and the influence that the measurementfluid has on the polishing capability is reduced, as described above.

In a preferred aspect of the present invention, the solvent comprises analkaline solvent of a silica slurry. A silica slurry for polishing asilicon oxide film (SiO₂) contains an alkaline solvent (pH 10-11) inorder to secure a removal rate. If the alkaline solvent is diluted bypure water, the removal rate is lowered. According to the presentinvention, the alkaline solvent of the silica slurry is used as ameasurement fluid for thereby reducing the influence on the removalrate. The alkaline solvent is KOH or NH₄OH, for example.

In a preferred aspect, the solvent comprises a surface-active agentsolution of a ceria slurry. The ceria slurry for polishing a siliconoxide film (SiO₂) or an STI wafer contains a surface-active agentsolution as a solvent for thereby keeping a low removal rate andsecuring step characteristics. If the surface-active agent is diluted bypure water, then the removal rate is increased, and the stepcharacteristics may be deteriorated. According to the present invention,the surface-active agent solution of the ceria slurry is used as themeasurement fluid, and hence the influence on the removal rate and thestep characteristics can be reduced. The surface-active agent ispreferably a cationic surface-active agent. The cationic surface-activeagent may be ammonium polycarboxylate or the like.

In a preferred aspect of the present invention, the supply passage ofthe fluid supply device is made of a highly chemical-resistant materialsuch as resin or ceramic. The supply passage may be coated with a highlychemical-resistant material, and such a structure is included in theabove structure. According to the present invention, the supply passagemember is prevented from being damaged by the solvent which is used as ameasurement fluid.

Furthermore, the substrate is prevented from being contaminated byimpurity which has been eluted from the supply passage member due to theeffect of the solvent. It is preferable that the members for guidingmeasurement light and reflected light, e.g., optical fibers, have thesame structure as described above.

According to another aspect of the present invention, there is provideda substrate measuring device for measuring a film on a substrateincorporated in a substrate polishing apparatus having a polishing tableagainst which a substrate is pressed, characterized in that thepolishing table has a fluid supply device for supplying a measurementfluid, and the fluid supply device supplies a solvent used in apolishing slurry as the measurement fluid.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a polishing table againstwhich a substrate is pressed; a light emission and reception device foremitting measurement light from the polishing table to the substrate andreceiving reflected light from the substrate so as to measure a film onthe substrate; and a fluid supply device for supplying a measurementfluid, which transmits the measurement light and the reflected light, toan area where the measurement light is applied; wherein the fluid supplydevice supplies a highly viscous fluid as the measurement fluid, and thehighly viscous fluid is more viscous than a polishing slurry. Typically,the highly viscous fluid is liquid. However, the highly viscous fluid isnot limited to liquid. The highly viscous fluid may be sol or the like.In the present invention, gel may be included in the highly viscousfluid.

According to the present invention, since the highly viscous fluid issupplied as the measurement fluid, the diffusion of the slurry flowinginto the measuring area can be reduced. Therefore, the influence thatthe slurry has on film measurement is reduced, thus increasing themeasuring capability.

Further, according to the present invention, the highly viscous fluid isused as the measurement fluid, and hence the amount of the measurementfluid that flows out can be reduced. Because of the above diffusionreducing capability, the measuring capability is increased, and hencethe same measuring capability can be obtained even if an amount of thehighly viscous fluid to be supplied is smaller than an amount of waterto be supplied. Thus, the amount of the measurement fluid flowing outcan be reduced. Since the amount of the measurement fluid flowing out isreduced, the influence that the measurement fluid has on the polishingcapability is reduced. According to the present invention, therefore,the influence that the measurement fluid has on the polishing capabilityis reduced while the measuring capability is maintained.

According to another aspect of the present invention, there is provideda substrate measuring device incorporated in a substrate polishingapparatus having a polishing table against which a substrate is pressedfor emitting measurement light from the polishing table to the substrateand receiving reflected light from the substrate so as to measure a filmon the substrate, the substrate measuring device comprising: a fluidsupply device for supplying a measurement fluid, which transmits themeasurement light and the reflected light, to an area where themeasurement light is applied; wherein the fluid supply device supplies ahighly viscous fluid as the measurement fluid, and the highly viscousfluid is more viscous than a polishing slurry.

According to another aspect of the present invention, there is provideda substrate polishing apparatus comprising: a polishing table againstwhich a substrate is pressed; a light emission and reception device foremitting measurement light from the polishing table to the substrate andreceiving reflected light from the substrate so as to measure a film onthe substrate; and a fluid supply device for supplying a measurementfluid, which transmits the measurement light and the reflected light, toan area where the measurement light is applied; wherein the fluid supplydevice supplies a gas as the measurement fluid.

According to the present invention, since a gas is used as themeasurement fluid, the slurry is removed from the measuring area, andhence an excellent measuring capability can be obtained. Even if the gasflows out, the slurry is not diluted, and hence the influence that themeasurement fluid has on the polishing capability can be reduced.According to the present invention, therefore, the influence that themeasurement fluid has on the polishing capability is reduced whilemaintaining the measuring capability. The gas may comprise air,nitrogen, or a noble gas.

In a preferred aspect of the present invention, a light-emitting memberand a light-receiving member are made of a water-repellent material.Alternatively, the light-emitting member and the light-receiving membermay have a water-repellent-finished surface, respectively. With thisstructure, when the slurry is attached to the light-emitting member andthe light-receiving member, the attached slurry can be easily removed.

Although various aspects of the present invention have been describedabove, the present invention is not limited to the above substratepolishing apparatuses. For example, another aspect of the presentinvention includes a substrate measuring device incorporated in asubstrate polishing apparatus. The substrate measuring device isincorporated in a substrate polishing apparatus which has a polishingtable against which a substrate is pressed, and measures a film on thesubstrate. The polishing table has a fluid supply device for supplying ameasurement fluid, and the fluid supply device supplies a solvent usedin a polishing slurry as the measurement fluid. With this structure, theinfluence that the measurement fluid has on the polishing capability canbe reduced.

In a preferred aspect of the present invention, there is provided asubstrate processing apparatus which incorporates the substratepolishing apparatus described above. In a preferred aspect of thepresent invention, there are also provided a substrate polishing methodwhich is carried out with use of the above substrate polishingapparatus, and a substrate measuring method which is carried out withuse of the above substrate measuring device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing an entire structure of a substrate polishingapparatus according to an embodiment of the present invention;

FIG. 2 is a view showing another example of an entire structure of thesubstrate polishing apparatus shown in FIG. 1;

FIG. 3 is a view showing a substrate processing system having thesubstrate polishing apparatus according to the embodiment of the presentinvention;

FIG. 4 is a view showing a structure of the substrate polishingapparatus according to the first embodiment of the present invention;

FIGS. 5A and 5B are views showing the relationship between a position ofan outlet and a water flow;

FIG. 6 is a view showing a modification of the substrate polishingapparatus according to the first embodiment of the present invention;

FIGS. 7A through 7H are views showing various structures of a pipepiece;

FIG. 8 is a view showing a structure of a substrate polishing apparatusaccording to a second embodiment of the present invention;

FIGS. 9A and 9B are views each showing a pipe unit of the substratepolishing apparatus according to the second embodiment of the presentinvention;

FIGS. 10A and 10B are views each showing a modification of the pipeunit;

FIG. 11 is a view showing a structure of a substrate polishing apparatusaccording to a third embodiment of the present invention;

FIG. 12 is a view showing a structure of a substrate polishing apparatusaccording to a fourth embodiment of the present invention;

FIG. 13 is a view showing a structure of a substrate polishing apparatusaccording to a fifth embodiment of the present invention;

FIG. 14 is a view showing a modification of the substrate polishingapparatus according to the fifth embodiment of the present invention;

FIG. 15 is a view showing a structure of a substrate polishing apparatusaccording to a sixth embodiment of the present invention;

FIG. 16 is a view showing a structure of a substrate polishing apparatuswhen replacing a polishing pad according to a seventh embodiment of thepresent invention;

FIG. 17 is a view showing a structure of the substrate polishingapparatus when polishing a substrate according to the seventh embodimentof the present invention;

FIG. 18 is a view showing a modification of the seventh embodiment;

FIG. 19 is a view showing a structure of a modification of the substratepolishing apparatus when polishing a substrate according to the seventhembodiment of the present invention;

FIG. 20 is a view showing a structure of a modification of the substratepolishing apparatus when polishing a substrate according to the seventhembodiment of the present invention;

FIG. 21A is an enlarged view showing a mount portion for a patch piecein detail;

FIG. 21B is a view showing a structure in which a protection cover ismounted on the mount portion;

FIG. 22 is a view showing a structure of a modification of the substratepolishing apparatus when polishing a substrate according to the seventhembodiment of the present invention;

FIG. 23 is a view illustrating the substrate polishing apparatus havinga protection cover of another structure;

FIG. 24 is a view illustrating the substrate polishing apparatus havinga patch piece of another structure;

FIGS. 25A and 25B are views showing a structure of a substrate polishingapparatus according to an eighth embodiment of the present invention;

FIGS. 26A and 26B are views showing a first modification of thesubstrate polishing apparatus according to the eighth embodiment of thepresent invention;

FIGS. 27A and 27B are views showing a second modification of thesubstrate polishing apparatus according to the eighth embodiment of thepresent invention;

FIGS. 28A and 28B are views showing a third modification of thesubstrate polishing apparatus according to the eighth embodiment of thepresent invention;

FIGS. 29A and 29B are views showing a fourth modification of thesubstrate polishing apparatus according to the eighth embodiment of thepresent invention;

FIGS. 30A and 30B are views showing a fifth modification of thesubstrate polishing apparatus according to the eighth embodiment of thepresent invention;

FIG. 31 is a view showing a polishing pad used in a substrate polishingapparatus according to a ninth embodiment of the present invention;

FIG. 32 is a view showing the manner of attaching the polishing padwhich is incorporated in the substrate polishing apparatus according tothe ninth embodiment of the present invention;

FIG. 33 is a view showing a structure of the substrate polishingapparatus according to the ninth embodiment of the present invention;

FIG. 34 is a view showing a polishing pad used in a substrate polishingapparatus according to a tenth embodiment of the present invention;

FIG. 35A is a view showing orbits of a through hole traced with therotation of a rotatable table and positions of a substrate;

FIG. 35B is a view showing orbits of the through hole when rotationalspeeds of the rotatable table and the substrate are changed;

FIG. 35C is a view showing orbits of the through hole according to thepresent embodiment;

FIG. 36 is a view showing a modification of the tenth embodiment of thepresent invention;

FIG. 37 is a view showing a polishing pad used in a substrate polishingapparatus according to an eleventh embodiment of the present invention;

FIG. 38 is a view showing a polishing pad used in a modification of thesubstrate polishing apparatus according to the eleventh embodiment ofthe present invention;

FIG. 39 is a view showing an example of a substrate polishing apparatusaccording to a twelfth embodiment of the present invention;

FIGS. 40A and 40B are views showing an expendable component replacementdoor provided on a polishing table of the substrate polishing apparatusshown in FIG. 1, FIG. 40A being a plane view and FIG. 40B being a sideview;

FIGS. 41A and 41B are views showing a modification of the expendablecomponent replacement door, FIG. 41A being a plane view and FIG. 41Bbeing a side view;

FIGS. 42A and 42B are views showing a modification of the expendablecomponent replacement door, FIG. 42A being a plane view and FIG. 42Bbeing a side view;

FIGS. 43A and 43B are views showing a modification of the expendablecomponent replacement door, FIG. 43A being a plane view and FIG. 43Bbeing a side view;

FIG. 44 is a view showing a modification of the expendable componentreplacement door;

FIG. 45 is a view showing a substrate polishing apparatus according toanother embodiment of the present invention;

FIG. 46 is a view showing a substrate polishing apparatus according toanother embodiment of the present invention;

FIG. 47 is a view showing an example of an optical rotary joint;

FIG. 48 is a view showing an example of the optical rotary joint;

FIGS. 49A and 49B are views showing an example of the optical rotaryjoint;

FIGS. 50A through 50C are views each showing an example of the opticalrotary joint;

FIGS. 51A and 51B are views showing an example of a rotary joint for ameasurement fluid;

FIG. 52 is a view showing the rotary joint for a measurement fluid;

FIG. 53 is a view showing an example of the rotary joint for ameasurement fluid;

FIGS. 54A and 54B are views showing an example of the rotary joint for ameasurement fluid; and

FIG. 55 is a view showing an example of a sensor incorporated in thesubstrate polishing apparatus shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First, an entire structure of a substrate polishing apparatus will bedescribed below with reference to FIG. 1.

FIG. 1 shows a substrate polishing apparatus according to a firstembodiment of the present invention. FIG. 2 shows another example of anentire structure of the substrate polishing apparatus shown in FIG. 1.The substrate polishing apparatus 10 is a so-called chemical mechanicalpolishing (CMP) apparatus, and has a rotatable table (polishing table)12 and a top ring 14. A polishing pad 16 is attached to the rotatabletable 12. As the polishing pad 16, a fixed abrasive type polishing padwhich is formed by fixing polishing abrasive particles by a binder agentsuch as epoxy may be used in addition to a polishing cloth made ofpolyurethane foam, a nonwoven fabric type polishing cloth, and a suedetype polishing cloth. The top ring 14 supports a substrate 18 on a lowersurface thereof and is rotated together with the substrate 18. The topring 14 presses the substrate 18 against the polishing pad 16 at alocation away from a center of the rotatable table 12. Slurry (polishingabrasive) for polishing is supplied between the polishing pad 16 and thesubstrate 18. The slurry is supplied from a slurry container 20 througha slurry supply passage 22. The substrate 18 is rotated in the presenceof the slurry in a state such that the substrate 18 is pressed againstthe polishing pad 16 on the rotatable table 12. Further, the rotatabletable 12 is rotated. The substrate 18 is thus polished.

The substrate polishing apparatus 10 is used to polish a thin filmformed on the substrate 18. Polishing is completed when the thickness ofthe thin film becomes a predetermined value. In the present embodiment,determination of completion is referred to as end point detection. Thesubstrate polishing apparatus 10 has a film thickness measuring device24, which will be described below, for end point detection.

A film to be measured by the film thickness measuring device 24 is aninsulating film such as a silicon oxide film or a metal film, forexample. The film thickness measuring device 24 has a sensor 26 mountedin the rotatable table 12, and also has a power supply unit 28, acontroller unit 30, a light source unit 32, and a photometer unit 34,which are mounted on a lower surface of the rotatable table 12.

The power supply unit 28 receives electric power via a rotary connector36 and supplies the electric power to the respective units in the filmthickness measuring device 24. The controller unit 30 controls theentire system of the film thickness measuring device 24. The lightsource unit 32 supplies measurement light to the sensor 26, and themeasurement light is applied to the substrate 18 through the sensor 26.The sensor 26 receives reflected light from the substrate 18 andtransmits it to the photometer unit 34. In the photometer unit 34, lightsignals are converted into electric signals. The electric signals areprocessed in the controller unit 30.

The controller unit 30 is connected to an optical characteristiccalculating unit 38 via the rotary connector 36, and the opticalcharacteristic calculating unit 38 is connected to an opticalcharacteristic determining unit 40. The signals processed in thecontroller unit 30 are transmitted to the optical characteristiccalculating unit 38, which calculates optical characteristics such asthe film thickness, the reflection intensity, and the spectrum. Theoptical characteristic determining unit 40 determines the opticalcharacteristics such as the film thickness and performs end pointdetection to determine whether or not the film thickness reaches apredetermined value. The determined results are sent to a polishingcontrol unit 42, which controls the entire system of the substratepolishing apparatus 10.

The film thickness measuring device 24 also has a supply passage 44 tosupply a measurement fluid to the sensor 26, and a discharge passage 46to discharge the measurement fluid from the sensor 26. The supplypassage 44 is connected to a tank, which is not shown, via a rotaryjoint 48. The discharge passage 46 is connected to a pump 50 forcompulsorily discharging a measurement fluid in the sensor 26 and apolishing liquid such as slurry flowing into the measurement fluid.

The optical characteristic determining unit 40 of the film thicknessmeasuring device 24 stores a most recent data of light signal as areference data. When bubbles and slurry enter a gap between the sensor26 and the substrate 18 to cause light signal to be greatly changed withrespect to the reference data, the optical characteristic determiningunit 40 treats such light signal as an abnormal data. A threshold fordetermining that light signal is an abnormal data can be set by anoperator.

In the present embodiment, the measurement fluid is pure water. Thesupply passage 44 and the discharge passage 46 are constituted bysuitable pipes or the like. The supply passage 44 and the dischargepassage 46 may include jackets provided in the rotatable table 12.

As shown in FIG. 1, the supply passage 44 has a parallel section 67, andthe parallel section 67 comprises a main passage 54 and a sub passage56. The main passage 54 and the sub passage 56 have supply controlvalves 58 and 60. The main passage 54 is used to supply pure water at ahigh flow rate and eject the pure water in the sensor 26. On the otherhand, the sub passage 56 has an orifice (not shown) and is used tosupply pure water at a low flow rate. The supply control valves 58 and60 are opened and closed to switch low-flow-rate supply of pure waterand ejection of pure water. The supply control valves 58 and 60 may notbe closed depending on the flow rate of pure water to be supplied.

Further, the discharge passage 46 has a discharge control valve 62. Thedischarge control valve 62 is used to control the timing of compulsorydischarge. The discharge control valve 62 and the supply control valves58, 60 comprise an electromagnetic valve and constitute anelectromagnetic valve unit, which is not shown. The electromagneticvalve unit is mounted on a lower surface of the rotatable table 12 aswith other units.

Depending on a type of rotary joint, it may be required to secure acertain flow rate of the measurement fluid which is supplied from thesupply pump 2102 to the rotary joint 48. In the case where theabove-mentioned flow rate is larger than a flow rate of the measurementfluid to be supplied to the sensor 26, a rotary joint discharge passage2200 is provided for discharging the measurement fluid from the rotaryjoint 48, as shown in FIG. 2. In this case, a flow meter (not shown) isprovided on the supply passage 44 and a flow meter 2201 is provided onthe rotary joint discharge passage 2200, so that a flow rate of themeasurement fluid to be supplied to the sensor 26 is controlled byadjusting flow rates of the measurement fluids which are measured by theabove flow meters. Practically, a flow rate of the measurement fluid tobe supplied to the sensor 26 is controlled when maintenance of thesubstrate polishing apparatus is not carried out. There is a differencein a flow rate of the measurement fluid between when the sensor 26measures a film on the substrate 18 and when the substrate polishingapparatus is in an idling state. Specifically, when measuring the film,the flow rate is controlled at an appropriate value so as to secure astability of measuring performance, i.e., slurry-removal performance. Onthe other hand, when the substrate polishing apparatus in the idlingstate, the flow rate is controlled at a small value so as to preventoptical fibers, which will be described later, from being dried and toprevent entry of the slurry. In order to further increase an accuracy ofthe above control, the fluid chamber 2100 is designed to allow itsstatic pressure to be measured, and the supply pump 2102, the supplycontrol valves 58, 60, and the discharge control valve 62 are designedto allow their operations to be monitored.

In order to maintain the flow rate of the measurement fluid within anappropriate range, allowed values are set in advance so that the flowrates of the measurement fluids to be supplied to the rotary joint 48and the sensor 26 are restricted below the allowed values, respectively.The allowed values depend on sampling times of the flow meters, openingand closing cycles of the supply control valves 58, 60, and therotational speed of the rotatable table 12. Therefore, the substratepolishing apparatus is designed to allow an operator to set therotational speed of the rotatable table 12 and to input the aboveallowed values. Further, in order to allow the operator to check thecontrol conditions, the substrate polishing apparatus has a display suchas a touch panel which shows at least one of the flow rate of themeasurement fluid supplied to the rotary joint 48, the flow rate of themeasurement fluid discharged through the rotary joint discharge passage2200, and the flow rate of the measurement fluid supplied to the sensor26.

Practically, if the flow rate of the measurement fluid deviates from anappropriate range, a determining unit (not shown) determines that anerror has occurred and then performs a necessary step such as stoppingthe polishing process. However, when an operating state of the substratepolishing apparatus is switched between a state of measuring a film bythe sensor 26 and a state of idling, the flow rate of the measurementfluid is quickly changed. In such a case, the above determining unittends to determine that an error has occurred and thus may cause thesubstrate polishing apparatus to malfunction. Therefore, error detectionis not performed when the operating state of the substrate polishingapparatus is switched.

When the polishing pad 16 is replaced with new one, an operator operatesthe touch panel or other control panel to switch the operating state ofthe substrate polishing apparatus so that supply of the measurementfluid is stopped. Further, any of the supply control valves 58, 60 andthe discharge control valve 62 can be opened as desired by apredetermined setting. In order to prevent slurry from being supplieddue to the malfunction during the stoppage of the supply of themeasurement fluid, the slurry is not supplied while the replacement ofthe polishing pad 16 is carried out. Furthermore, the supply of themeasurement fluid is stopped when a protection cover, which will bedescribed later, is attached to the sensor 26.

In case of supplying pure water as the measurement fluid, the substratepolishing apparatus may employ the following structure. A pure watersupply device (not shown) is provided between the supply pump 2102 andthe fluid chamber 2100 or between the supply pump 2102 and the rotaryjoint 48. The above pure water supply device comprises a pressurecontrol valve, a flow meter, and a flow rate control valve. Each of thepressure control valve, the flow meter, and the flow rate control valvehas some portions which are made of a non-metal material such as SiC inorder to prevent metal contamination from occurring when the pure wateris brought into contact with such portions. The pure water supply deviceis constructed to suppress a pulsation of a valve-inlet pressure. Inthis embodiment, for example, the pressure control valve has a structurewhich utilizes an air pressure to perform a pressure control, the flowrate control valve is a type of needle valve, and the flow meter is atype of turbine flow meter. This flow meter converts a measured valueinto electric signal, so that the converted electric signal is sent to acontroller (not shown) for thereby monitoring and controlling a flowrate of the pure water, i.e., the measurement fluid.

The substrate polishing apparatus 10 also has a water jacket 64 forcooling disposed in the rotatable table 12. The water jacket 64 isconnected to a water tank, which is not shown, through the rotary joint48.

A slip ring (not shown) is provided below the rotary joint 48. The slipring has a rotary-side metal member disposed at rotary joint side and afixed-side metal member disposed at slip ring side. The rotary-sidemetal member and the fixed-side metal member are brought into contactwith each other at all times so as to allow electric signal and electricpower to be transmitted therebetween. In the case where the rotary joint48 has a hollow at a center of rotation thereof, the slip ring isdisposed in alignment with the center of rotation of the rotary joint48. With this structure, it is possible to transmit light from thefixed-side to the rotary-side. The rotary joint 48 has some portionswhich are made of a non-metal material such as SiC in order to preventmetal contamination from occurring when the measurement fluid is broughtinto contact with such portions.

The rotary joint may have at least three circular passages which arecentrally aligned with the center of rotation. One of the three passagesis used as a supply passage for the measurement fluid, and the othersare used as cooling fluid passages each for a cooling fluid by which therotatable table 12 is cooled. Preferably, the second passage from thecenter of rotation is used as the supply passage for the measurementfluid. In this case, if the measurement fluid discharged from the rotaryjoint discharge passage 2200 is used as the cooling fluid for coolingthe rotatable table 12, it is possible to reduce an amount of themeasurement fluid discharged from the rotary joint discharge passage2200.

FIG. 3 shows an entire arrangement of a substrate processing apparatus66 having the substrate polishing apparatuses 10. The substrateprocessing apparatus 66 has a substrate cassette holding section 68, asubstrate moving device 70, and cleaning chambers 72 as well as thesubstrate polishing apparatuses 10. The substrate 18 as a workpiece tobe polished is delivered from the substrate cassette holding section 68to the substrate polishing apparatus 10. The polished substrate 18 iscleaned in the cleaning chamber 72 and returned to the substratecassette holding section 68.

Each of the substrate polishing apparatuses 10 has a dresser 15 disposedadjacent to the rotatable table 12. The dresser 15 is used to dress thepolishing pad 16 whose polishing capability has been lowered due topolishing operation and initialize (regenerate, repair, or dress) thepolishing capability of the polishing pad 16. Structural details and adressing operation of the dresser 15 will be described below. A brush isattached to a lower surface of the dresser 15. The polishing pad 16 isrotated while a polishing surface 90 (see FIG. 4) is supplied with adressing liquid (pure water or the like). The dresser 15 is also rotatedand then the lower surface thereof is pressed against the polishingsurface 90 for a predetermined period of time. The polishing capabilityof the polishing pad 16 is thus initialized by the dresser 15. Thedresser 15 may have a structure in which diamond particles areelectrodeposited on the lower surface thereof.

Further, the substrate processing apparatus 66 has working windows 74 ina chamber in which the substrate polishing apparatuses 10 are installed.Slurry is supplied through nozzles 76 to the rotatable tables 12. Thenozzle 76 serves as the slurry supply passage 22 shown in FIG. 1. Ameasurement fluid is supplied to the rotatable table 12 from below,although not shown.

Next, there will be described the features of the structure of thepresent embodiment.

FIG. 4 is a view showing the substrate polishing apparatus 10 accordingto the first embodiment of the present invention, and showing ameasuring area of the rotatable table 12 at an enlarged scale. Astructure shown in FIG. 4 corresponds to the sensor 26 in the entirestructure of the substrate polishing apparatus 10 shown in FIG. 1. Asalready described, the polishing pad 16 is placed on a polishing padmount surface 78 of the rotatable table 12, and the substrate 18 is heldin contact with the polishing pad 16. The supply passage 44 and thedischarge passage 46 are formed in the rotatable table 12 and extend inparallel to each other.

A light-emitting optical fiber 80 and a light-receiving optical fiber 82are disposed in the supply passage 44 and extend in parallel to eachother. The light-emitting optical fiber 80 and the light-receivingoptical fiber 82 are connected respectively to the light source unit 32and the photometer unit 34 (see FIG. 1). The light-emitting opticalfiber 80 applies measurement light, which is supplied from the lightsource unit 32, to the substrate 18. The light-receiving optical fiber82 receives reflected light from the substrate 18 and transmits thereceived light to the photometer unit 34. In the present embodiment, thelight-emitting optical fiber 80 and the light-receiving optical fiber 82constitute a light emission and reception device for emitting themeasurement light and receiving the reflected light.

The polishing pad 16 has a through hole 84 formed therein, and thesupply passage 44 and the discharge passage 46 communicate with thethrough hole 84. A pipe piece 86 for providing the supply passage 44 inthe through hole 84 is mounted on the rotatable table 12. In the presentembodiment, the pipe piece 86 serves as an outlet portion of the supplypassage 44, and an end portion of the pipe piece 86 serves as an outlet88 for the measurement fluid. The outlet 88 serves as a supply port forsupplying the measurement fluid, which is supplied through the supplypassage 44, into the through hole 84. The pipe piece 86 is positioned inthe through hole 84. Specifically, the outlet 88 is positioned above therotatable table 12 and is also positioned in the vicinity of thepolishing surface 90 of the polishing pad 16.

The pipe piece 86 comprises a cylindrical member and is fastened to therotatable table 12 by a screw mechanism 92. Specifically, the screwmechanism 92 comprises a male screw formed on the pipe piece 86 and afemale screw formed on the rotatable table 12, which are fittedtogether. The pipe piece 86 has a flange 87 provided on an outercircumferential surface thereof. When the pipe piece 86 is fastened tothe rotatable table 12 by the screw mechanism 92, the flange 87 is heldin close contact with the polishing pad mount surface 78 of therotatable table 12. The outlet 88 on an upper end of the pipe piece 86is thus positioned at an appropriate vertical position in the throughhole 84.

In the substrate polishing apparatus 10 according to the presentembodiment, the measurement fluid such as pure water is supplied throughthe supply passage 44 and discharged through the discharge passage 46.Therefore, the through hole 84 is filled with transparent pure water,and hence the polishing slurry is prevented from entering the throughhole 84, thus allowing measurement with use of transmitted light to beperformed.

In the present embodiment, particularly, since the pipe piece 86 servingas the outlet portion of the supply passage 44 extends into the throughhole 84, the influence that the slurry has on the measurement accuracyis greatly reduced. This feature will be described below with referenceto FIGS. 5A and 5B.

FIGS. 5A and 5B are views each illustrating the relationship between aposition of the outlet 88 and a water flow. In FIG. 5A, a distancebetween the outlet 88 and the substrate 18 is large. This structurecorresponds to an apparatus in which the outlet portion of the supplypassage 44 is disposed in the rotatable table 12. On the other hand, inFIG. 5B, a distance between the outlet 88 and the substrate 18 issmaller than the distance in the arrangement shown in FIG. 5A. Thisstructure corresponds to the structure of the present embodiment, i.e.,the structure in which the outlet 88 is disposed in the through hole 84.

According to the arrangement shown in FIG. 5B, a gap between the outlet88 and the substrate 18 is smaller than a gap in the arrangement shownin FIG. 5A. Therefore, in the arrangement shown in FIG. 5B, pure wateris vigorously ejected from the outlet 88 at a flow velocity greater thanthat of the arrangement shown in FIG. 5A. The pure water that has beenejected from the outlet 88 produces a flow of pure water along thesubstrate 18. Consequently, the arrangement shown in FIG. 5B is moreeffective than the arrangement shown in FIG. 5A in removing a polishingabrasive from an area where measurement light is applied, which islocated in front of the outlet portion, by the flow of pure watersupplied from the supply passage 44.

According to the present embodiment, since the pipe piece 86 serving asthe outlet portion of the supply passage 44 is positioned in the throughhole 84 of the polishing pad 16, the outlet 88 of the supply passage 44is close to the substrate 18. Therefore, a flow velocity of fluidsupplied from the outlet 88 is increased at the outlet 88, and the fluidis vigorously ejected from the gap between the substrate 18 and theoutlet 88 toward the outside of the supply passage 44, thus forming theflow of the fluid along the substrate 18. The flow of the fluid caneffectively remove the polishing abrasive from the area wheremeasurement light is applied, which is located in front of the outletportion.

According to the present embodiment, furthermore, the pipe piece 86serving as the outlet portion is detachably mounted on the rotatabletable 12. Therefore, since the pipe piece 86 can be mounted after thepolishing pad 16 is attached to the rotatable table 12, the polishingpad 16 can be easily mounted on the rotatable table 12. Further, if thepipe piece 86 is removed before the polishing pad 16 is removed, thepolishing pad 16 can be easily removed without causing damage to thepipe piece 86.

FIG. 6 is a view showing a modification of the above embodiment. Thismodification has the same basic structure as the above substratepolishing apparatus 10. However, in this modification, a plate-likerestriction 94 having an opening smaller than a cross-sectional area ofthe supply passage 44 is mounted on the outlet portion of the pipe piece86. With this structure, the area of the outlet 88 of the pipe piece 86is smaller than the cross-sectional area of the supply passage 44.

In the structure shown in FIG. 6, since the area of the outlet 88 issmaller than the area of the supply passage 44, the flow velocity of thepure water ejected from the outlet 88 of the supply passage 44 becomeslarge. Thus, it is possible to increase the ability to remove thepolishing abrasive from the area where measurement light is applied,which is located in front of the outlet portion.

In this modification, the restriction 94 is provided so that the area ofthe outlet 88 is smaller than the area of the supply passage 44.Alternatively, the outlet of the pipe piece may have a tapered shapesuch that the area of the outlet becomes gradually small.

Although the cylindrical pipe piece 86 constitutes the outlet portion ofthe supply passage 44 in the above embodiment, a pipe piece of differenttype may be employed alternatively. FIGS. 7A through 7H are viewsshowing various types of pipe pieces that can be employed in the presentinvention. FIG. 7A shows the cylindrical pipe piece 86 employed in thepresent embodiment. FIG. 7B shows a pipe piece 96 whose outer surfaceand hole have a hexagonal cross section. In contrast thereto, a pipepiece 98 shown in FIG. 7C has an outer surface having a hexagonal crosssection, and a pipe piece 100 shown in FIG. 7D has a hole having ahexagonal cross section. A pipe piece 102 shown in FIG. 7E has an outersurface having a star-shaped cross section and a hole having a circularcross section. A pipe piece 104 shown in FIG. 7F has an outer surfacehaving a circular cross section and has a hole having a star-shapedcross section. Both pipe pieces 106, 108 respectively shown in FIGS. 7Gand 7H comprise a cylindrical pipe piece. The pipe piece 106 has twonotches 110 provided near the outlet 88, and the pipe 108 has fournotches 110 provided near the outlet 88. These notches 110 are engagedwith a tool when the pipe pieces 106, 108 are installed and removed.When the pipe pieces 106, 108 are disposed very closely to the substrate18, pure water in the supply passage 44 can be released through thenotches 110. FIGS. 7A through 7H only show an example of the pipe piece,and it is possible to select a pipe piece having another type ofstructure.

In the above embodiment, the pipe piece 86 has the screw mechanism 92comprising the male screw on the pipe piece 86 and the female screw onthe rotatable table 12, so that the pipe piece 86 is fastened to therotatable table 12 by the screw mechanism 92. Alternatively, the pipepiece 86 may be fastened to the rotatable table 12 by any of othermechanisms. For example, the pipe piece 86 may be inserted into therotatable table 12 so as to be attached thereto, or may be magneticallyattached to the rotatable table 12 by a permanent magnet or anelectromagnet. The pipe piece 86 may be bonded to the rotatable table12.

FIG. 8 is a view showing a substrate polishing apparatus 10 according toa second embodiment of the present invention, and showing a measuringarea of the rotatable table 12 at an enlarged scale. As with the firstembodiment, the polishing pad 16 is mounted on the rotatable table 12,and the substrate 18 is held in contact with the polishing pad 16.

In the present embodiment, the polishing pad mount surface 78 of therotatable table 12 has a recess 112 formed therein. A pipe unit 116serving as the outlet portion of the supply passage 44 is mounted on apipe unit mount surface 114 constituting a bottom of the recess 112. Therotatable table 12 has the supply passage 44 for supplying pure waterfor measurement and the discharge passage 46 for discharging the purewater, and the supply passage 44 and the discharge passage 46 areexposed at the pipe unit mount surface 114. A light-emitting baseoptical fiber 118 and a light-receiving base optical fiber 120 extendingin parallel to each other are disposed in the rotatable table 12. Thelight-emitting base optical fiber 118 and the light-receiving baseoptical fiber 120 have respective end surfaces exposed at the pipe unitmount surface 114.

The pipe unit 116 has a pipe piece 122, a light-emitting optical fiber124, and a light-receiving optical fiber 126. As with the firstembodiment, the pipe piece 122 has an upper end serving as an outlet 128for a measurement fluid, and the outlet 128 is positioned in the throughhole 84. Specifically, the outlet 128 is positioned above the rotatabletable 12 and below the polishing surface 90 of the polishing pad 16. Thepipe piece 122 has a solid lower portion serving as a fiber support 130that supports the light-emitting optical fiber 124 and thelight-receiving optical fiber 126. The fiber support 130 has acommunication passage 132 formed therein for allowing the interior ofthe pipe piece 122 and the supply passage 44 in the rotatable table 12to communicate with each other. The light-emitting optical fiber 124 andthe light-receiving optical fiber 126 are disposed in parallel to eachother in the pipe piece 122, and are supported by the fiber support 130.The light-emitting optical fiber 124 and the light-receiving opticalfiber 126 constitute a light emission and reception device.

The light-emitting optical fiber 124 and the light-receiving opticalfiber 126 have respective tip end portions 134, 136 positioned in thethrough hole 84. The light-emitting optical fiber 124 and thelight-receiving optical fiber 126 extend to a lower surface of the pipeunit 116, and have respective end surfaces exposed at the lower surfaceof the pipe unit 116.

A mounting structure for the pipe unit 116 will be described below. FIG.9A is a view showing the pipe piece 122 of the pipe unit 116, and FIG.9B is a view showing a unit base for mounting the pipe unit 116 on therotatable table 12.

As shown in FIG. 9A, the pipe piece 122 has a flange provided on anouter circumferential surface thereof. An annular fastening member 140is disposed so as to surround the fiber support 130. The fasteningmember 140 has an inwardly projecting portion whose pressing surfaceengages with the flange of the pipe piece 122. The fastening member 140has a female screw formed on an inner circumferential surface thereof. Akey 138 for determining a direction in which the pipe piece 122 ismounted is disposed on an outer circumferential surface of the fibersupport 130 of the pipe piece 122 and extends along the extendingdirection of the pipe piece 122.

As shown in FIG. 9B, a unit base 142 has a disk 144 to be mounted on thepipe unit mount surface 114, a cylindrical portion 146 extendingupwardly from the disk 144, and a projecting portion 148 extendingdownwardly from the disk 144. The disk 144, the cylindrical portion 146,and the projecting portion 148 are integrally formed with each other.The disk 144 has four screw holes 150 formed therein by which the unitbase 142 is fixed to the pipe unit mount surface 114. The fiber support130 of the pipe piece 122 is received in the cylindrical portion 146.The cylindrical portion 146 has a key slot 152 formed on an innercircumferential surface thereof, and the key 138 is fitted into the keyslot 152. The cylindrical portion 146 has a male screw formed on anouter circumferential surface thereof. The projecting portion 148 isreceived in a hole formed in the pipe unit mount surface 114.

A light-emitting junction optical fiber 125 and a light-receivingjunction optical fiber 127 are provided in the unit base 142. Thelight-emitting junction optical fiber 125 serves to join thelight-emitting optical fiber 124 and the light-emitting base opticalfiber 118 to each other, and the light-receiving junction optical fiber127 serves to join the light-receiving optical fiber 126 and thelight-receiving base optical fiber 120 to each other. The unit base 142has a communication passage 133 for joining the communication passage132 in the pipe piece 122 and the supply passage 44 in the rotatabletable 12 to each other.

With the above structure, the unit base 142 is fixed to the rotatabletable 12 by screws, and the pipe piece 122 is fastened to the unit base142 by the fastening member 140.

An operation of mounting the pipe unit 116 will be described below.First, the unit base 142 shown in FIG. 9B is placed on the pipe unitmount surface 114 of the rotatable table 12, and is then fixed to thepipe unit mount surface 114 by screws which are inserted into the screwholes 150 of the unit base 142. The unit base 142 is placed on the pipeunit mount surface 114 such that the projecting portion 148 of the unitbase 142 is inserted in the hole formed in the pipe unit mount surface114. At this time, the light-emitting base optical fiber 118 that isexposed at the pipe unit mount surface 114 and the light-emittingjunction optical fiber 125, the light-receiving base optical fiber 120and the light-receiving junction optical fiber 127, and the supplypassage 44 and the communication passage 133 are aligned with eachother, respectively. Then, the pipe piece 122 is fitted into thecylindrical portion 146 of the unit base 142 in such an orientation thatthe key 138 of the fiber support 130 is inserted in the key slot 152 ofthe cylindrical portion 146 of the unit base 142, and hence the pipepiece 122 is mounted on the unit base 142. In this state, thelight-emitting junction optical fiber 125, the light-receiving junctionoptical fiber 127, and the communication passage 133 of the unit base142 are aligned with the light-emitting optical fiber 124, thelight-receiving optical fiber 126, and the communication passage 132 ofthe pipe piece 122, respectively. With the pipe piece 122 being mountedon the unit base 142, the fastening member 140 is turned to press theflange of the pipe piece 122, so that the pipe piece 122 is fastened tothe unit base 142. The light-emitting junction optical fiber 125 and thelight-emitting optical fiber 124 are joined to each other, and thelight-receiving junction optical fiber 127 and the light-receivingoptical fiber 126 are also joined to each, thus allowing those opticalfibers to guide light.

The pipe unit 116 is detachably mounted on the rotatable table 12 asdescribed above. The pipe unit 116 is removed when the polishing pad 16is replaced, so that the polishing pad 16 can be easily replaced withoutbeing obstructed by the pipe piece 122, the light-emitting optical fiber124, and the light-receiving optical fiber 126.

The light-emitting optical fiber 124 and the light-receiving opticalfiber 126 are disposed in such a state that the tip end portions 134,136 thereof are positioned upwardly of the rotatable table 12. The tipend portion 134 of the light-emitting optical fiber 124 and the tip endportion 136 of the light-receiving optical fiber 126 are positionedclosely to the substrate 18, and hence the reflected light from thesubstrate 18 can be received efficiently.

The pipe piece 122 extends into the through hole 84, and the outlet 128is positioned in the through hole 84. Therefore, as with the firstembodiment, the polishing abrasive can effectively be removed from thearea where measurement light is applied.

The pipe unit 116 serving as the outlet portion is detachably mounted onthe rotatable table 12. Therefore, the outlet portion (the pipe unit116) may be mounted after the polishing pad 16 is attached to therotatable table 12, so that the polishing pad 16 can be easily attachedto the rotatable table 12. Further, the outlet portion may be removedbefore the polishing pad 16 is removed, so that the polishing pad 16 canbe easily removed without causing damage to the outlet portion.

FIGS. 10A and 10B are views showing another mounting structure for thepipe unit 116 of the above embodiment. FIG. 10A shows a pipe piece 122,and FIG. 10B shows a unit base 142. As with the pipe piece 122 describedabove, the pipe piece 122 has a solid lower portion serving as a fibersupport 130 that supports the light-emitting optical fiber 124 and thelight-receiving optical fiber 126. The fiber support 130 has a malescrew formed on an outer circumferential surface thereof. As shown inFIG. 10A, a key slot 152 is formed near a lower end thereof below themale screw. The key slot 152 serves to determine a direction in whichthe pipe piece 122 is mounted.

As shown in FIG. 10B, the unit base 142 has a cylindrical portion 154for receiving the lower end of the fiber support 130. The cylindricalportion 154 has a key 138 formed on an inner circumferential surfacethereof. The key 138 engages with the key slot 152 of the fiber support130.

The cylindrical portion 154 has a communication passage 133 for allowingthe supply passage 44 and the interior of the pipe piece 122 tocommunicate with each other, and also has the light-emitting junctionoptical fiber 125 and the light-receiving junction optical fiber 127.

An annular fastening member 140 is disposed so as to surround thecylindrical portion 154. The fastening member 140 has a female screwformed on an inner circumferential surface thereof. The fastening member140 has a lower end projecting inwardly and positioned between a flangeof the cylindrical portion 154 and the rotatable table (not shown). Theflange projects outwardly from an upper portion of the cylindricalportion 154.

In order to mount the pipe unit 116 onto the rotatable table 12, first,the cylindrical portion 154 of the unit base 142 is mounted on the pipeunit mount surface 114. At this time, the fastening member 140 isdisposed between the cylindrical portion 154 and the non-illustratedrotatable table. The unit base 142 may be mounted on the rotatable table12 by bonding, welding, pressure-fitting, or screw engagement with aflange. Alternatively, the unit base 142 may be mounted by a boltinserted into the cylindrical portion 154 from below the rotatable table12.

Then, the pipe piece 122 is inserted into the cylindrical portion 154 ofthe unit base 142 such that the key 138 of the cylindrical portion 154is fitted into the key slot 152 of the fiber support 30. With the pipepiece 122 being inserted in the cylindrical portion 154, the fasteningmember 140 is turned to fasten the pipe piece 122 to the unit base 142.In this case also, the pipe unit 116 can be mounted on the rotatabletable 12.

In the above embodiment, the pipe piece 122 has the light-emittingoptical fiber 124 and the light-receiving optical fiber 126, and theunit base 142 has the light-emitting junction optical fiber 125 and thelight-receiving junction optical fiber 127. Alternatively, alight-emitting optical fiber 124 and a light-receiving optical fiber 126which extend continuously from the pipe piece 122 to the unit base 142may be employed. This structure can be achieved by the followingstructure. The pipe piece 122 has a cylindrical optical fiber fixingmember made of a resilient material. An optical fiber is insertedthrough the optical fiber fixing member and is then fastened by theoptical fiber fixing member. The unit base 142 has a light-emittingoptical fiber 124 and a light-receiving optical fiber 126 whose tip endportions project upwardly. The light-emitting optical fiber 124 and thelight-receiving optical fiber 126 projecting upwardly of the unit base142 are inserted into the optical fiber fixing member, so that the tipend portions of the light-emitting optical fiber 124 and thelight-receiving optical fiber 126 are positioned in the pipe piece 122.Then, the optical fiber fixing member is tightened to fix thelight-emitting optical fiber 124 and the light-receiving optical fiber126 in place. The light-emitting optical fiber 124 and thelight-receiving optical fiber 126 may be fixed together by the opticalfiber fixing member, or may be fixed separately by respective opticalfiber fixing members which are provided for the light-emitting opticalfiber 124 and the light-receiving optical fiber 126, respectively.

In the above embodiment, the pipe piece 122 is mounted by the fasteningmember 140. However, the present invention is not limited to such astructure. For example, the pipe unit 116 may be mounted on the pipeunit mount surface 114 by a bolt and a nut. Alternatively, the pipe unit116 may be bonded to the pipe unit mount surface 114.

FIG. 11 is a view showing a substrate polishing apparatus 10 accordingto a third embodiment of the present invention, and showing a measuringarea of the rotatable table 12 at an enlarged scale. As with the firstembodiment, the polishing pad 16 is placed on the polishing pad mountsurface 78 of the rotatable table 12, and the substrate 18 is held incontact with the polishing pad 16. The rotatable table 12 incorporatestherein the supply passage 44 for supplying pure water for measurementto the through hole 84 and the discharge passage 46 for discharging thepure water from the through hole 84. The light-emitting optical fiber 80and the light-receiving optical fiber 82 are disposed in the supplypassage 44. The light-emitting optical fiber 80 and the light-receivingoptical fiber 82 constitute a light emission and reception device.

The substrate polishing apparatus 10 has a pipe piece 156 serving as anoutlet portion of the supply passage 44. The pipe piece 156 comprises acylindrical member extending from the inside of the rotatable table 12to a position upward of the rotatable table 12 in a directionperpendicular to the polishing surface 90. The pipe piece 156 has anoutlet 158 positioned in the through hole 84. Specifically, the outlet158 is positioned below the polishing surface 90.

The supply passage 44 disposed in the rotatable table 12 comprises atube. An outside diameter of the supply passage 44 is substantiallyequal to an inside diameter of the pipe piece 156. A tip end portion ofthe supply passage 44 is inserted in the pipe piece 156. The pipe piece156 is slidable in the extending direction of the supply passage 44. Thepipe piece 156 has a lower portion thicker than an upper portionthereof, thereby constituting a supported portion 160. The rotatabletable 12 has a hole 162 in which the supported portion 160 of the pipepiece 156 is inserted. A spring 164 is mounted on a lower surface of thesupported portion 160 for thereby urging the pipe piece 156 to moveupwardly. The hole 162 formed in the rotatable table 12 has an upper endserving as a contact surface 168 for receiving a step 166 of thesupported portion 160. When the step 166 is brought into contact withthe contact surface 168, a movement of the pipe piece 156 under anurging force of the spring 164 is limited, and the pipe piece 156 isthus positioned.

The pipe piece 156 is urged upwardly by the spring 164 and hence theoutlet 158 projects from the rotatable table 12. Therefore, when thepipe piece 156 is pressed toward the rotatable table 12, the pipe piece156 is moved in a sliding motion to be accommodated in the rotatabletable 12. The hole 162 formed in the rotatable table 12 has a sizeenough to allow the pipe piece 156 to move to a position where theoutlet of the pipe piece 156 is accommodated in the rotatable table 12.

An operation of installing the polishing pad 16 according to the presentembodiment will be described below. First, the polishing pad 16 isplaced on the polishing pad mount surface 78 of the rotatable table 12.At this time, the polishing pad 16 is positioned such that the pipepiece 156 projecting from the rotatable table 12 is inserted in thethrough hole 84 formed in the polishing pad 16. In an initial stage ofplacing the polishing pad 16 on the rotatable table 12, the polishingpad 16 is roughly positioned. When the polishing pad 16 is placed on thepipe piece 156 and the pipe piece 156 is pressed toward the rotatabletable 12, the pipe piece 156 is moved into the rotatable table 12against the urging force of the spring 164, and accommodated in therotatable table 12. Then, the position of the polishing pad 16 on therotatable table 12 is adjusted. Specifically, the polishing pad 16 ismoved on the rotatable table 12 so as to bring the through hole 84 overthe pipe piece 156. When the through hole 84 is positioned over the pipepiece 156, the pipe piece 156 is moved upwardly by the urging force ofthe spring 164, and projects from the rotatable table 12. That is, theoutlet 158 of the pipe piece 156 projects into the through hole 84.

In this manner, when the pipe piece 156 is pressed by the polishing pad16 placed on the rotatable table 12, the pipe piece 156 is accommodatedin the rotatable table 12. Therefore, the pipe piece 156 does notobstruct the installation of the polishing pad 16. When the through hole84 of the polishing pad 16 and the pipe piece 156 are aligned with eachother, the pipe piece 156 projects into the through hole 84.Consequently, the through hole 84 and the pipe piece 156 can be easilypositioned with respect to each other.

With the substrate polishing apparatus 10 according to the thirdembodiment, since the outlet 158 of the pipe piece 156 is positioned inthe through hole 84, the polishing abrasive can effectively be removedfrom the area where measurement light is applied, as with the firstembodiment.

The pipe piece 156 serving as the outlet portion is urged to move towardthe polishing surface 90 by the spring 164 as an urging means, so thatthe pipe piece 156 is disposed in the through hole 84. The outletportion can be moved toward the rotatable table 12 against the urgingforce of the spring 164. When replacing the polishing pad 16, if thepolishing pad 16 is placed on the outlet portion, the outlet portion ispushed by the polishing pad 16 and accommodated in the rotatable table12. When the through hole 84 of the polishing pad 16 and the outletportion are aligned with each other, the outlet portion is urged by thespring 164 to project into the through hole 84. Therefore, since theoutlet portion does not obstruct the installation of the polishing pad16, the polishing pad 16 can be easily positioned.

FIG. 12 is a view showing a substrate polishing apparatus 10 accordingto a fourth embodiment of the present invention, and showing a measuringarea of the rotatable table 12 at an enlarged scale. As with the firstembodiment, the polishing pad 16 is placed on the polishing pad mountsurface 78 of the rotatable table 12, and the substrate 18 is held incontact with the polishing pad 16. The rotatable table 12 incorporatestherein the supply passage 44 and the discharge passage 46 which extendin parallel to each other. The supply passage 44 accommodates thereinthe light-emitting optical fiber 80 and the light-receiving opticalfiber 82 which extend in parallel to each other. The light-emittingoptical fiber 80 and the light-receiving optical fiber 82 constitute alight emission and reception device.

The substrate polishing apparatus 10 has a pipe piece 170 serving as anoutlet portion of the supply passage 44. The pipe piece 170 comprises acylindrical member extending from the inside of the rotatable table 12to a position upward of the rotatable table 12 in a directionperpendicular to the polishing surface 90. The pipe piece 170 has anoutlet 172 positioned in the through hole 84. Specifically, the outlet172 is positioned below the polishing surface 90. An outercircumferential surface of the pipe piece 170 is held in contact withthe inner surface of the supply passage 44 within the rotatable table12. The pipe piece 170 is vertically movable along the supply passage44.

A piezoelectric element 174 is attached to a lower portion of the pipepiece 170. A voltage generator 176 for applying voltage is connected tothe piezoelectric element 174. The substrate polishing apparatus 10 alsohas an electrostatic distance meter 178 for measuring a distance betweenthe outlet 172 and the substrate 18. The electrostatic distance meter178 is connected to the controller unit 30. The controller unit 30 sendsa command signal to the voltage generator 176 based on a distancemeasured by the electrostatic distance meter 178 so as to control themovement of the pipe piece 170.

Since the pipe piece 170 is attached to the piezoelectric element 174,when voltage is applied to the piezoelectric element 174, the pipe piece170 is moved along the supply passage 44 so as to change the position ofthe pipe piece 170. Therefore, the position of the pipe piece 170 can bechanged at any time such as when replacing or dressing the polishing pad16 or when polishing the substrate 18. While the substrate 18 ispolished, the electrostatic distance meter 178 measures a distancebetween the outlet 172 and the substrate 18, and the position of thepipe piece 170 is adjusted based on the measured distance. Specifically,when the polishing pad 16 is worn by polishing to cause the substrate 18to be positioned closely to the outlet 172, the pipe piece 170 islowered to avoid a contact between the pipe piece 170 and the substrate18. If the pipe piece 170 is moved toward the substrate 18 insofar asthe pipe piece 170 is kept out of contact with the substrate 18 whilethe substrate 18 is polished, a flow velocity of pure water ejected fromthe gap between the substrate 18 and the outlet 172 can be large.Therefore, the polishing abrasive can effectively be removed from thearea where measurement light is applied. When dressing the polishing pad16, the pipe piece 170 is lowered to a position where the pipe piece 170is kept out of contact with the dresser, or the pipe piece 170 isaccommodated in the rotatable table 12, so that the pipe piece 170 isprevented from being scraped by the dressing process. When replacing thepolishing pad 16, the pipe piece 170 is accommodated in the rotatabletable 12. Since the pipe piece 170 does not project from the polishingpad mount surface 78, the pipe piece 170 is not obstructive, and hencethe polishing pad 16 can be easily attached.

As described above, with the substrate polishing apparatus 10 accordingto the fourth embodiment, since the outlet portion can be moved by thepiezoelectric element 174 serving as an outlet portion moving means, theoutlet portion can be moved into the through hole 84 after the polishingpad 16 is attached to the rotatable table 12.

The outlet portion can be moved and accommodated in the rotatable table12 before the polishing pad 16 is removed. Therefore, the polishing pad16 can be easily replaced without causing damage to the outlet portion.The outlet portion projects from the rotatable table 12 to be positionedclosely to the substrate 18. Therefore, the flow velocity of the fluidsupplied from the supply passage 44 is increased at the outlet portion,and the fluid is vigorously ejected from the gap between the substrate18 and the outlet portion toward the outside of the supply passage 44,thus forming a flow along the substrate 18. The flow of the fluid caneffectively remove the polishing abrasive from the area wheremeasurement light is applied, which is located in front of the outletportion. Since the distance between the substrate 18 and the outletportion is measured by the electrostatic distance meter 178, it ispossible to adjust the position of the outlet portion according to thethickness of the polishing pad 16 which has been scraped by the dressingprocess, and hence an positional relationship between the substrate 18and the outlet portion can be kept appropriately.

FIG. 13 is a view showing a substrate polishing apparatus 10 accordingto a fifth embodiment of the present invention, and showing a measuringarea of the rotatable table 12 at an enlarged scale. The substratepolishing apparatus 10 according to the fifth embodiment has the samebasic structure as the substrate polishing apparatus 10 according to thefourth embodiment. However, the substrate polishing apparatus 10according to the fifth embodiment is different from the substratepolishing apparatus 10 according to the fourth embodiment in that whilethe pipe piece 170 is movable in the fourth embodiment, thelight-emitting optical fiber 80 and the light-receiving optical fiber 82are movable in the fifth embodiment.

The supply passage 44 formed in the rotatable table 12 accommodatestherein the light-emitting optical fiber 80 and the light-receivingoptical fiber 82 extending in parallel to each other. The light-emittingoptical fiber 80 and the light-receiving optical fiber 82 constitute alight emission and reception device. The light-emitting optical fiber 80and the light-receiving optical fiber 82 are connected to the lightsource unit 32 and the photometer unit 34, respectively. Thelight-emitting optical fiber 80 applies measurement light supplied fromthe light source unit 32 to the substrate 18. The light-receivingoptical fiber 82 receives reflected light from the substrate 18 andtransmits the received light to the photometer unit 34.

The pipe piece 170 serving as an outlet portion of the supply passage 44comprises a cylindrical member extending from the inside of therotatable table 12 to a position upward of the rotatable table 12 in adirection perpendicular to the polishing surface 90.

The pipe piece 170 is fixed to the supply passage 44. The pipe piece 170has an outlet 172 positioned in the through hole 84. Specifically, theoutlet 172 is positioned below the polishing surface 90.

The piezoelectric element 174 is connected to the light-emitting opticalfiber 80 and the light-receiving optical fiber 82. The voltage generator176 for applying voltage is connected to the piezoelectric element 174.The substrate polishing apparatus 10 also has a calculating unit 180 forcalculating an amount of received light detected by the photometer unit34. The calculating unit 180 is connected to the controller unit 30. Thecontroller unit 30 sends a command signal to the voltage generator 176based on the amount of the received light calculated by the calculatingunit 180 so as to control the movement of the light-emitting opticalfiber 80 and the light-receiving optical fiber 82.

In the substrate polishing apparatus 10, the piezoelectric element 174is attached to the light-emitting optical fiber 80 and thelight-receiving optical fiber 82. When voltage is applied to thepiezoelectric element 174, the light-emitting optical fiber 80 and thelight-receiving optical fiber 82 is moved along the supply passage 44,and hence the positions thereof can be changed. The controller unit 30for controlling the voltage generator 176 which applies voltage to thepiezoelectric element 174 is connected to the calculating unit 180 whichcalculates the amount of light received by the light-receiving opticalfiber 82. The control unit 30 controls the piezoelectric element 174based on the amount of the received light calculated by the calculatingunit 180, so that the light-emitting optical fiber 80 and thelight-receiving optical fiber 82 can be moved so as to increase theamount of the reflected light to be received.

The amount of the received light is calculated by the photometer unit 34and the calculating unit 180, and the piezoelectric element 174 iscontrolled based on the amount of the received light. With thisstructure, the positions of the light-emitting optical fiber 80 and thelight-receiving optical fiber 82 can be adjusted while the substrate 18is polished. When the tip end portion 182 of the light-emitting opticalfiber 80 and the tip end portion 184 of the light-receiving opticalfiber 82 are close to the substrate 18, the amount of the reflectedlight to be received is increased. However, if the tip end portions 182,184 are too close to the substrate 18, then the amount of the reflectedlight to be received is reduced. Therefore, when the polishing pad 16 isworn by polishing or dressing to cause the distances between the tip endportions 182, 184 and the substrate 18 to become small, the positions ofthe light-emitting optical fiber 80 and the light-receiving opticalfiber 82 can be adjusted based on the amount of the received light,thereby increasing a rate at which the reflected light is received.

According to the fifth embodiment, since the outlet 172 of the pipepiece 170 is positioned in the through hole 84, the polishing abrasivecan effectively be removed from the area where measurement light isapplied, as with the first embodiment.

The light emission and reception device can be disposed in the throughhole 84, and can be thus brought closely to the substrate 18 for therebyreceiving the reflected light efficiently. Because the light emissionand reception device is movable, the light emission and reception devicecan be accommodated in the rotatable table 12 when the polishing pad 16is replaced, and thus does not obstruct the replacement of the polishingpad 16.

FIG. 14 is a view showing a modification of the substrate polishingapparatus according to the fifth embodiment. This modification isdifferent in that a ball screw 186 is employed instead of thepiezoelectric element 174 for moving the light-emitting optical fiber 80and the light-receiving optical fiber 82. The ball screw 186 is mountedon the light-emitting optical fiber 80 and the light-receiving opticalfiber 82. The ball screw 186 is connected to a ball screw actuatingcircuit 188. The calculating unit 180 for calculating an amount ofreceived light detected by the photometer unit 34 is connected to thecontroller unit 30. The controller unit 30 sends a command signal to theball screw actuating circuit 188 based on the amount of the receivedlight calculated by the calculating unit 180 so as to control themovement of the light-emitting optical fiber 80 and the light-receivingoptical fiber 82.

According to this modification, as with the above embodiment, thecontrol unit 30 controls the ball screw 186 based on the amount of thereceived light calculated by the calculating unit 180, so that thelight-emitting optical fiber 80 and the light-receiving optical fiber 82can be moved so as to increase the amount of the reflected light to bereceived. The above modification is also applicable to the fourthembodiment. In this case, the outlet portion moving means is constitutedby of the ball screw and the ball screw actuating circuit.

The light-emitting optical fiber 80 and the light-receiving opticalfiber 82 may be vertically movable independently of each other. Withthis structure, the vertical positions of the tip end portions 182, 184can be adjusted separately or only one of the vertical positions of thetip end portions 182, 184 can be adjusted in order to optimize theamount of light received by the light-receiving optical fiber 82.

FIG. 15 is a view showing a substrate polishing apparatus 10 accordingto a sixth embodiment of the present invention, and showing a measuringarea of the rotatable table 12 at an enlarged scale. The substratepolishing apparatus 10 according to the sixth embodiment has the samebasic structure as the substrate polishing apparatus 10 according to thefourth embodiment (FIG. 12). However, while the pipe piece 170 ismovable in the fourth embodiment, the light-emitting optical fiber 80and the light-receiving optical fiber 82 together with the pipe piece170 are movable in the fifth embodiment.

Specifically, in the sixth embodiment, the light-emitting optical fiber80 and the light-receiving optical fiber 82 as well as the pipe piece170 serving as the outlet portion are connected to the piezoelectricelement 174. Thus, the light-emitting optical fiber 80 and thelight-receiving optical fiber 82 together with the pipe piece 170 arevertically movable.

The light-emitting optical fiber 80 and the light-receiving opticalfiber 82 are movable along the supply passage 44. Therefore, if the tipend portion 182 of the light-emitting optical fiber 80 and the tip endportion 184 of the light-receiving optical fiber 82 together with thepipe piece 170 are moved closely to the substrate 18 when polishing, thereflected light from the substrate 18 can efficiently be received. Whenreplacing the polishing pad 16, the light-emitting optical fiber 80 andthe light-receiving optical fiber 82 together with the pipe piece 170are accommodated in the rotatable table 12 so as not to obstruct thereplacement of the polishing pad 16.

According to the sixth embodiment, as with the fourth embodiment, thepolishing abrasive can effectively be removed from the area wheremeasurement light is applied by moving the pipe piece 170 so as toposition the outlet 172 in the through hole 84 and bringing the outlet172 closely to the substrate 18.

Since the light emission and reception device can be disposed in thethrough hole 84 so as to be positioned closely to the substrate 18, thereflected light can be received efficiently. Further, since the lightemission and reception device is movable together with the outletportion, the light emission and reception device can be accommodated inthe rotatable table 12 when replacing the polishing pad 16. Therefore,the light emission and reception device does not obstruct thereplacement of the polishing pad 16.

The process of measuring the distance between the pipe piece 170 or theoptical fibers 80, 82 and the substrate 18, and the moving mechanism forthe pipe piece 170, the optical fibers 80, 82, or the pipe piece 170with the optical fibers 80, 82 have been described above with referenceto FIGS. 11 through 14. However, the process of measuring the distanceand the moving mechanism are not limited to the above embodiments, butcombination thereof may be changed as needed. Further, other types ofsensors and moving mechanisms may also be employed.

The light-emitting optical fiber 80, the light-receiving optical fiber82, and the pipe piece 170 may be vertically movable independently ofeach other. With such a structure, the vertical positions of thelight-emitting optical fiber 80, the light-receiving optical fiber 82,and the pipe piece 170 can be adjusted independently so as to optimizethe amount of received light and a flow velocity of a measurement fluidwhich is ejected toward the substrate 18. It is desirable to control thepipe piece 170 and the optical fibers 80, 82 so that the distancebetween the pipe piece 170 and the substrate 18, and the distancebetween the optical fibers 80, 82 and the substrate 18 are keptconstant, respectively. It is also desirable to move the pipe piece 170and the optical fibers 80, 82 integrally and simultaneously. In thesecases, it is possible to reduce an influence due to mixture of theslurry with the measurement fluid and change of the amount of light, andhence properties of the substrate 18 can be measured accurately.

In the present embodiment, the pipe piece 170, the light-emittingoptical fiber 80, and the light-receiving optical fiber 82 are movablewith use of the piezoelectric element 174. Alternatively, a ball screwcan be employed instead of the piezoelectric element 174. In theembodiments shown in FIGS. 11 through 14, in order to prevent a fluidfrom leaking from a gap between the supply passage 44 and the polishingtable 12, a seal mechanism such as a cover for covering the gap may beprovided.

FIG. 16 is a view showing a substrate polishing apparatus 10 accordingto a seventh embodiment of the present invention, and showing ameasuring area of the rotatable table 12 at an enlarged scale. As withthe first embodiment described above, the polishing pad 16 is placed onthe polishing pad mount surface 78 of the rotatable table 12. Therotatable table 12 incorporates therein the supply passage 44 and thedischarge passage 46 extending in parallel to each other. The polishingpad 16 has the through hole 84 formed therein, and the supply passage 44and the discharge passage 46 communicate with the through hole 94.

The light-emitting optical fiber 80 and the light-receiving opticalfiber 82 are disposed in parallel to each other in the supply passage44. The light-emitting optical fiber 80 and the light-receiving opticalfiber 82 constitute a light emission and reception device. Thelight-emitting optical fiber 80 and the light-receiving optical fiber 82project from the rotatable table 12, and the tip end portions 182, 184thereof are positioned in the through hole 84.

The substrate polishing apparatus 10 has a protection cover 190 fittedin the through hole 84. The protection cover 190 is detachably mountedon the rotatable table 12 by bolts 192. As described below, theprotection cover 190 is mounted when the polishing pad 16 is replaced.

An operation of replacing the polishing pad 16 in the present embodimentwill be described below. When replacing the polishing pad 16, theprotection cover 190 is fitted in the through hole 84, and is then fixedto the rotatable table 12 by the bolts 192. Then, the old polishing pad16 is removed, and a new polishing pad 16 is attached. The polishing pad16 is attached so that the protection cover 190 fixed to the rotatabletable 12 is fitted into the through hole 84 of the polishing pad 16.After the polishing pad 16 is attached, the bolts 192 are removed, andthen the protection cover 190 is removed from the rotatable table 12.

When the polishing pad 16 is replaced, the supply passage 44 and thedischarge passage 46 are covered by the protection cover 190. Therefore,it is possible to protect the light-emitting optical fiber 80 and thelight-receiving optical fiber 82 whose tip end portions 182, 184 projectupwardly from the supply passage 44 and the rotatable table 12. Sincethe polishing pad 16 is attached in such a manner that the protectioncover 190 is fitted into the through hole 84, the polishing pad 16 canbe easily positioned. Consequently, the polishing pad 16 can be easilyreplaced.

The tip end portions of the light-emitting optical fiber 80 and thelight-receiving optical fiber 82 are positioned above the rotatabletable 12. Therefore, the tip end portions 182, 184 of the light-emittingoptical fiber 80 and the light-receiving optical fiber 82 are positionedclosely to the substrate 18, and hence the reflected light from thesubstrate 18 can be received efficiently.

According to the seventh embodiment, since the protection cover 190 isreceived in the through hole 84 of the polishing pad 16, the polishingpad 16 can be replaced while the protection cover 190 is mounted. Theprotection cover 190 covers an opening, serving as the supply passage44, of the rotatable table 12. Therefore, even if the outlet portion ofthe supply passage 44 and the light emission and reception deviceproject from the polishing pad mount surface 78, for example, thepolishing pad 16 can be replaced while the supply passage 44 isprotected by the protection cover 190.

FIG. 17 is a view showing an example of the substrate polishingapparatus 10 in a state of polishing the substrate 18 and measuring afilm on the substrate 18. A patch piece 194 is mounted instead of theprotection cover 190. The patch piece 194 has holes 196 formed thereinfor allowing the supply passage 44 and the discharge passage 46 tocommunicate with the through hole 84. The patch piece 194 also has atube portion 198 for allowing the supply passage 44 to extend into thethrough hole 84. The tube portion 198 serves as the outlet portion ofthe supply passage 44, and has an outlet 200 positioned in the throughhole 84.

The outlet 200 is positioned in the through hole 84 by providing thepatch piece 194. Accordingly, as with the first embodiment, thepolishing abrasive can effectively be removed from the area wheremeasurement light is applied.

FIG. 18 is a view showing a modification of the above embodiment, andshowing a measuring area of the rotatable table 12 at an enlarged scale.In this modification, the rotatable table 12 has a recess 191 in whichthe protection cover 190 is fitted. The protection cover 190 is mountedby being fitted in the recess 191 of the rotatable table 12. With thisstructure, the protection cover 190 can be easily mounted on and removedfrom the rotatable table 12.

FIG. 19 is a view showing a modification of the substrate polishingapparatus 10 in a state of polishing the substrate 18 and measuring afilm on the substrate 18. A patch piece 194 is mounted instead of theprotection cover 190 on the rotatable table 12. The patch piece 194 ismounted by being fitted in the recess 191 of the rotatable table 12. Thepatch piece 194 has a tube portion 198 for effectively removing thepolishing abrasive from the area where measurement light is applied, aswith the first embodiment. The patch piece 194 may not necessarily havethe tube portion 198.

FIG. 20 is a view showing a modification of the substrate polishingapparatus 10 in a state of polishing the substrate 18 and performing anend point detection. As shown in FIG. 20, a patch piece 194 employed inthis modification does not have a tube portion, and an outlet 200 of thesupply passage 44 is positioned on the polishing pad mount surface 78.Such a patch piece 194 can be employed in the substrate polishingapparatus 10.

FIG. 21A is an enlarged view showing in detail a mount area R for thepatch piece 194 shown in FIG. 20, and FIG. 21B is a view showing indetail a structure in which the protection cover 190 is mounted on themount area R. As shown in FIG. 21A, a mounting block 193 is installed inthe rotatable table 12. The block 193 has the supply passage 44 and thedischarge passage 46 formed therein. The patch piece 194 is fitted onthe mounting block 193. Openings 197 are formed in the patch piece 194,and pure water is supplied from the supply passage 44 to the throughhole 84 through the opening 197 and discharged from the dischargepassage 46 through the opening 197. O-rings 195 are attached to themounting block 193 and the patch piece 194, respectively, in order toprevent the pure water supplied to the through hole 84 from leaking intothe rotatable table 12.

As shown in FIG. 21B, the protection cover 190 has substantially thesame shape as the patch piece 194 shown in FIG. 21A. However, theprotection cover 190 does not have openings for allowing the supplypassage 44 and the discharge passage 46 to communicate with the throughhole 84.

FIG. 22 is a view showing another modification of the substratepolishing apparatus 10 in a state of polishing the substrate 18 andmeasuring a film on the substrate 18. In this modification, a diameterof the through hole 84 formed in the polishing pad 16 is equal to adiameter of the patch piece 194. Accordingly, after the polishing pad 16and the protection cover 190 attached thereto are replaced, theprotection cover 190 can be replaced with the patch piece 194. With thisstructure, the polishing pad 16 can be easily positioned by theprotection cover 190 when the polishing pad 16 is attached.

FIG. 23 is a view showing the substrate polishing apparatus 10 having aprotection cover of another structure. A protection cover 190 has arecess in which the tube portion 198 of the patch piece 194 is fitted.The protection cover 190 is mounted on the rotatable table 12 by fittingthe tube portion 198 into the recess.

With this structure, the polishing pad 16 is attached to the rotatabletable 12 in the following manner. First, the tube portion 198 is fittedinto the recess of the protection cover 190, so that the protectioncover 190 is mounted on the rotatable table 12. The position of theprotection cover 190 on the rotatable table 12 is thus determined. Then,the polishing pad 16 is attached such that the protection cover 190 isfitted into the through hole 84. In this manner, the polishing pad 16 ispositioned and attached to the rotatable table 12.

With this modification, the protection cover 190 has a function forprotecting the light-emitting optical fiber 80 and the light-receivingoptical fiber 82 disposed in the tube portion 198 and the supply passage44, and also has a function for positioning the polishing pad 16 withrespect to the rotatable table 12. Further, when the mounting operationof the polishing pad 16 is completed, the patch piece 194 having thetube portion 198 has been mounted. Therefore, when the protection cover190 is removed, a film on the substrate 18 can be measured immediately.

FIG. 24 is a view showing the substrate polishing apparatus 10 having apatch piece 194 capable of positioning the polishing pad 16. As shown inFIG. 24, the patch piece 194 has a guide protrusion 199 for guiding thethrough hole 84. The guide protrusion 199 projects from the rotatabletable 12 and an outer circumferential surface of the guide protrusion199 is held in contact with the inner circumferential surface of thethrough hole 84.

With this structure, the polishing pad 16 can be positioned byinstalling the polishing pad 16 such that the guide protrusion 199 isfitted in the through hole 84.

When the substrate 18 is polished in the above embodiment, the patchpiece 194 may not necessarily be mounted on a portion from which theprotection cover 190 has been removed. For example, the cylindrical pipepiece 86 in the first embodiment described above may be employed. Theprotection cover 190 according to the present embodiment may be usedwhen the polishing pad 16 is replaced in any of the substrate polishingapparatus 10 according to the other embodiments.

FIGS. 25A and 25B are views showing a substrate polishing apparatus 10according to an eighth embodiment of the present invention. FIG. 25Bshows a measuring area of the rotatable table 12 at an enlarged scale,and FIG. 25A shows the measuring area shown in FIG. 25B as viewed fromabove.

The discharge passage 46, the supply passage 44, and an auxiliary supplypassage 202 are disposed in parallel to each other in the rotatabletable 12. The polishing pad 16 has the through hole 84 formed therein,and the discharge passage 46, the supply passage 44, and the auxiliarysupply passage 202 communicate with the through hole 84. The supplypassage 44 accommodates therein the light-emitting optical fiber 80 andthe light-receiving optical fiber 82 extending in parallel to eachother. The auxiliary supply passage 202 is positioned at a forward ofthe supply passage 44 in the rotating direction of the rotatable table12. The rotating direction of the rotatable table 12 is indicated by thearrow R. The auxiliary supply passage 202 is formed by branching thesupply passage 44 at a position between the parallel section 52 and thesensor 26 shown in FIG. 1. Supply and stop of pure water to the supplypassage 44 and the auxiliary supply passage 202 are controlled by thesupply control valves 58, 60 at the same timing as each other.

In the substrate polishing apparatus 10, the measurement fluid such aspure water is supplied through the supply passage 44 and the auxiliarysupply passage 202 into the through hole 84, and is discharged throughthe discharge passage 46. The through hole 84 is filled with the purewater for measurement, thus preventing the polishing slurry fromentering the through hole 84.

The function of the auxiliary supply passage 202 will be describedbelow. When the rotatable table 12 is rotated, the slurry on thepolishing pad 16 moves relatively in a direction opposite to therotating direction of the rotatable table 12. Specifically, the slurrymoves in the direction indicated by the arrow S in FIG. 25B. Therefore,the slurry tends to flow into the through hole 84 from the forward inthe rotating direction of the rotatable table 12. Since the auxiliarysupply passage 202 is positioned at the forward of the supply passage 44in the rotating direction of the rotatable table 12, the slurry flowinginto the through hole 84 from the forward in the rotating direction isprimarily diluted by the pure water supplied from the auxiliary supplypassage 202. The primarily diluted slurry flows backward in the rotatingdirection of the rotatable table 12, and is then secondarily diluted bythe pure water supplied from the supply passage 44. The supply passage44 accommodates therein the light-emitting optical fiber 80 and thelight-receiving optical fiber 82, and the measuring area is locatedabove the supply passage 44. When the slurry reaches the measuring area,the slurry is diluted by the pure water supplied from the auxiliarysupply passage 202, and is further diluted by the pure water suppliedfrom the supply passage 44. As a result, the transparency of the purewater in the measuring area can be increased, and hence a film can bemeasured with increased accuracy.

FIGS. 26A and 26B are views showing a first modification of the aboveembodiment. The first modification has the same basic structure as theabove embodiment, but is different in that a pipe piece 204 is disposedin the auxiliary supply passage 202. The pipe piece 204 comprises acylindrical member extending along the auxiliary supply passage 202, andextends from the inside of the rotatable table 12 to a position upwardof the rotatable table 12. The pipe piece 204 has an outlet 206positioned in the through hole 84. Therefore, a flow velocity of purewater supplied from the auxiliary supply passage 202 is increased at theoutlet 206, and hence the pure water is vigorously ejected from the gapbetween the substrate 18 and the outlet 206 toward the outside of theauxiliary supply passage 202, thus forming a flow of pure water alongthe substrate 18. The flow of the pure water can restrict the entry ofthe slurry from the forward in the rotating direction of the rotatabletable 12, and can also dilute the slurry effectively.

FIGS. 27A and 27B are views showing a second modification of the aboveembodiment. In the second modification, the auxiliary supply passage 202has an arcuate shape surrounding the supply passage 44. As with thefirst modification, the pipe piece 204 extends along the auxiliarysupply passage 202, and the outlet 206 of the auxiliary supply passage202 is positioned in the through hole 84. According to the secondmodification, since the auxiliary supply passage 202 has a shapesurrounding the supply passage 44, the slurry flowing into the throughhole 84 from the forward in the rotating direction toward the supplypassage 44 can be primarily diluted. In addition thereto, the slurryflowing into the through hole 84 obliquely from the forward in therotating direction of the rotatable table 12 can also be primarilydiluted, thus increasing the transparency of the pure water in themeasuring area.

FIGS. 28A and 28B are views showing a third modification of the aboveembodiment. The third modification has the same basic structure as thefirst modification, but is different in that the auxiliary supplypassage 202 is smaller in size than the supply passage 44. Thelight-emitting optical fiber 80 and the light-receiving optical fiber 82are not disposed in the auxiliary supply passage 202, and hence theauxiliary supply passage 202 can be small in size. Since the auxiliarysupply passage 202 is small in size, a flow velocity of pure watersupplied from the auxiliary supply passage 202 can be increased. Thepure water flowing out of the auxiliary supply passage 202 forms a flowof the pure water along the substrate 18. The flow of the pure water canrestrict the entry of the slurry from the forward in the rotatingdirection, and can also dilute the slurry effectively.

FIGS. 29A and 29B are views showing a fourth modification of the aboveembodiment. The fourth modification has the same basic structure as thepresent embodiment, but is different in that the polishing pad 16 has asecond through hole 208. The second through hole 208 is formed in aposition aligned with the auxiliary supply passage 202, and pure watersupplied from the auxiliary supply passage 202 flows into the secondthrough hole 208. In this manner, even though the auxiliary supplypassage 202 is aligned with the second through hole 208 which isdifferent from the through hole 84, it is possible to effectivelyrestrict the entry of the slurry from the forward in the rotatingdirection, and dilute the slurry effectively, as with the aboveembodiment.

FIGS. 30A and 30B are views showing a fifth modification of the aboveembodiment. The fifth modification has the same basic structure as thesecond modification, but is different in that the rotatable table 12 hastwo discharge passages 210 on each side of the supply passage 44, inaddition to the structure of the second modification. With thisstructure, the slurry that has been diluted by the pure water from theauxiliary supply passage 202 can be discharged through the dischargepassages 210, and hence the transparency of the pure water in themeasuring area can be increased. The discharge passage 210 may be agroove or a hole formed in the surface of the polishing pad 16.

Although various modifications of the above embodiment have beendescribed above, other modifications than those shown in FIGS. 26through 30 may be made. For example, a pipe piece may be provided in thesupply passage 44 for thereby bringing the outlet of the supply passage44 closely to the substrate 18 so as to effectively remove the polishingabrasive from the area where measurement light is applied, as with thefirst embodiment. The polishing pad 16 may have an arcuate through hole84 in alignment with the arcuate auxiliary supply passage 202 describedin the second modification. The number, shape, and size of the auxiliarysupply passages 202 may be changed as desired.

FIG. 31 is a perspective view showing a polishing pad 16 for use in asubstrate polishing apparatus 10 according to a ninth embodiment, andFIG. 32 is a view showing a measuring area of the rotatable table 12 atan enlarged scale.

As shown in FIG. 31, the polishing pad 16 attached to the rotatabletable 12 comprises a circular thin plate and is made of polyurethane orthe like. A polishing pad piece 212 serving as part of the polishing pad16 is fitted in the polishing pad 16.

The polishing pad piece 212 has a surface connected smoothlycontinuously to the surface of the polishing pad 16, and has a throughhole 84 formed therein. The surface of the polishing pad piece 212 isflat. Specifically, the polishing pad piece 212 does not have a grooveand a dimple, which are formed on the polishing pad 16. The polishingpad piece 212 is made of the same material as the polishing pad 16.

As shown in FIG. 32, the polishing pad piece 212 has a mountingprotrusion 214 facing the rotatable table 12. The rotatable table 12 hasa hole 216 for receiving the mounting protrusion 214 of the polishingpad piece 212 therein. The mounting protrusion 214 and the hole 216 ofthe rotatable table 12 constitute a fixing means for securing thepolishing pad piece 212. With this structure, the polishing pad piece212 can be easily attached as a cartridge to the rotatable table 12.

FIG. 33 is a view showing the state in which the polishing pad 16 isattached to the rotatable table 12. An operation of attaching thepolishing pad 16 in the present embodiment will be described below withreference to FIGS. 31 and 32. As shown in FIG. 32, in order to attachthe polishing pad 16 to the rotatable table 12, first, the polishing padpiece 212 is mounted on the rotatable table 12. The mounting protrusion214 of the polishing pad piece 212 is fitted in the hole 216 formed inthe rotatable table 12, so that the polishing pad piece 212 is mountedon the rotatable table 12. Then, as shown in FIG. 33, the polishing pad16 is attached to the rotatable table 12 so that the polishing pad piece212 is fitted into an opening 218 of the polishing pad 16.

Since the polishing pad piece 212 has a flat surface 220 having nogroove and dimple, it is possible to restrict the entry of the slurryinto the through hole 84. Specifically, as shown in FIG. 32, thepolishing surface 90 of the polishing pad 16 has grooves 222 formedthereon for allowing the slurry and scraped particles to be washed outsmoothly from the polishing surface 90. The slurry may flow through thegrooves 222 into the through hole 84. The surface 220 of the polishingpad piece 212 having the through hole 84 is flat and does not have agroove which may serve as a passage for the slurry, and hence the slurrycan hardly flow on the surface 220. Since the polishing pad piece 212 ismade of the same material as the polishing pad 16, the polishing padpiece 212 does not cause damage to the substrate 18. Further, since thepolishing pad piece 212 is worn at the same rate as the polishing pad16, no step is formed between the polishing pad 16 and the polishing padpiece 212.

Furthermore, the polishing pad 16 can be easily positioned whenattaching the polishing pad 16 by mounting the polishing pad piece 212on the rotatable table 12 in advance.

According to the ninth embodiment, since the polishing pad piece 212does not have a groove and a dimple which may serve as a passage forallowing the polishing abrasive to flow into the through hole 84, theamount of the slurry flowing into the through hole 84 can be reduced.

In the above embodiment, the polishing pad piece 212 is made of the samematerial as the polishing pad 16. Alternatively, the polishing pad piece212 may be made of other material which is worn more easily than thepolishing pad 16. The polishing pad piece 212 may not have a polishingfunction.

FIG. 34 is a view showing a polishing pad 16 for use in a substratepolishing apparatus 10 according to a tenth embodiment. The polishingpad 16 has a portion as a flat surface 213 having no groove and dimplethereon, and a through hole 84 is formed in the flat surface 213. Thesize of the flat surface 213 and the size of the through hole 84 aredetermined in consideration of a processing condition which includes atype of slurry, a flow rate of the slurry, a rotational speed of therotatable table, a processing pressure, a supply flow rate of themeasurement fluid, a discharge flow rate of the measurement fluid, thenumber of the through holes 84, and an arrangement of the through holes84. In this embodiment, the through hole 84 having an elliptical shapeis formed in the flat surface 213. The through hole 84 has a major axisd1 ranging from 2 to 10 mm and a minor axis d2 ranging from 1 to 5 mm. Adistance d3 between an outer circumferential edge of the through hole 84and an outer circumferential edge of the flat surface 213 is 30 mm orless. Preferably, the major axis d1 of the through hole 84 ranges from 3to 8 mm, the minor axis d2 of the through hole 84 ranges from 2 to 4 mm,and the distance d3 between the outer circumferential edge of thethrough hole 84 and the outer circumferential edge of the flat surface213 is 10 mm or less. More preferably, the major axis d1 of the throughhole 84 ranges from 4 to 6 mm, the minor axis d2 of the through hole 84ranges from 2.5 to 3.5 mm, and the distance d3 between the outercircumferential edge of the through hole 84 and the outercircumferential edge of the flat surface 213 is 3 mm or less.

The through hole 84 is disposed in such a position that the through hole84 is not aligned with the center of rotation of the substrate 18 whenthe rotatable table 12 is rotated. FIG. 35A is a view showing thesubstrate 18 and orbits of the through hole 84 traced by the rotation ofthe rotatable table 12. FIG. 35B is a view showing orbits of the throughhole 84 traced on the substrate 18 when rotational speeds of therotatable table 12 and the substrate 18 are changed. FIG. 35C is a viewshowing orbits of the through hole 84 traced on the substrate 18 in thepresent embodiment. FIGS. 35B and 35C show the cases on the assumptionthat a distance from a center of rotation of the substrate 18 to acenter of the rotatable table 12 is substantially equal to a radius ofthe substrate 18.

First, there will be described the manner in which the orbit of thethrough hole 84 traced on the substrate 18 is changed depending on therotational speed of the rotatable table 12 and the rotational speed ofthe substrate 18 with reference to FIG. 35B. When the substrate 18 isnot rotated, the through hole 84 traces an orbit A1. When the substrate18 is rotated at the rotational speed which is one-half of therotational speed of the rotatable table 12, the through hole 84 tracesan orbit A2. When the rotational speeds of the substrate 18 and therotatable table 12 are equal to each other, the through hole 84 tracesan orbit A3. In this manner, the orbit of the through hole 84 traced onthe substrate 18 varies depending on the rotational speeds. Under ageneral polishing condition, since the rotational speeds of thesubstrate 18 and the rotatable table 12 are equal to each other, thethrough hole 84 traces the orbit A3. In this case, a profile of theright half of the substrate can be obtained, but a profile of the lefthalf of the substrate cannot be obtained.

As shown in FIG. 35B, if the orbit of the through hole 84 and the centerof rotation of the substrate 18 overlap each other, then polishingirregularities are liable to occur in the vicinity of the center ofrotation of the substrate 18. Consequently, it is preferable to set theposition of the through hole 84 such that the orbit of the through hole84 and the center of rotation of the substrate 18 are deviated from eachother. The degree in which the through hole 82 is deviated from thecenter of rotation of the substrate 18 is determined based on theprocessing condition. It is possible to reduce the polishingirregularities by setting the rotational speed of the rotatable table 12and the rotational speed of the substrate 18 to different values.

In the present embodiment, the through hole 84 is disposed at a positioncloser to the rotatable table 12 than to the center of rotation of thesubstrate 18. Accordingly, as shown in FIG. 35C, when the substrate 18is not rotated, the through hole 84 traces an orbit A4 on the substrate18, and when the substrate 18 is rotated at the same rotational speed asthe rotatable table 12, the through hole 84 traces an orbit A5. Underthe general polishing condition, since the through hole 84 traces theorbit A5, it is possible to obtain not only a profile of the right halfof the substrate 18, but also a profile of the left half of thesubstrate 18. The position where the through hole 84 is disposed hasbeen described above.

In the present embodiment, an area around the through hole 84 comprisesthe flat surface 213 which does not have a groove and a dimple which mayserve as a passage for the slurry. Thus, the flat surface 213 canprevent the slurry from flowing into the through hole 84, and hence afilm on the substrate 18 can be measured highly accurately with use ofmeasurement light. The polishing pad 16 has grooves or dimples on anarea other than the area around the through hole 84, thereby allowingthe slurry to be supplied and discharged efficiently.

Because the center of rotation of the substrate 18 is deviated from thecircular orbit of the through hole 84 traced by the rotation of therotatable table 12, it is possible to reduce the polishingirregularities formed on the polished substrate 18. Further, since thethrough hole 84 is deviated from the center of rotation of the substrate18 toward the center of the rotatable table 12, it is possible toincrease an area where the profile can be obtained under the generalpolishing condition.

FIG. 36 is a view showing a modification of the tenth embodiment. Inthis modification, a plurality of through holes 84 are formed in oneflat surface 213. Specifically, eight through holes 84 are disposed atequal intervals in the radial direction of the substrate 18 across thecenter of rotation of the substrate 18.

With this structure, a profile along the radial direction of thesubstrate 18 can be measured by applying measurement light to thesubstrate 18 through each of the through holes 84 so as to measure thefilm on the substrate 18. Since the through holes 84 are disposed acrossthe center of rotation, the polishing irregularities can be reduced.

In the case where an odd number of the through holes 84 are provided inthe polishing pad 16, it is preferable to dispose the through holes 84at positions including the center of rotation at equal intervals in viewof measuring a profile of the substrate 18.

A substrate polishing apparatus 10 according to an eleventh embodimentof the present invention has the same structure as the substratepolishing apparatus 10 (see FIG. 4) according to the first embodiment,but is different in that an inner circumferential surface of thepolishing pad 16 has a water repellency.

FIG. 37 is a view showing the polishing pad 16 near a through hole 84 atan enlarged scale in the eleventh embodiment. The polishing pad 16 has atwo-layer structure comprising a surface layer pad 228 and a lower layerpad 230. The surface layer pad 228 is made of a closed-cell resin havinga water repellency, e.g., IC1000 (trade name) manufactured by Rodel,Inc. The lower layer pad 230 is made of a non-woven fabric materialhaving water absorption, e.g., SUBA400 (trade name) manufactured byRodel, Inc. A portion of the lower layer pad 230 which is exposed in thethrough hole 84 is covered by a resin coating 232 for repelling water.

With this structure, the pure water supplied to the through hole 84hardly seeps into the polishing pad 16, thereby suppressing the propertychange of the polishing pad 16 to reduce the change in the polishingcharacteristics of the polishing pad 16.

FIG. 38 is a view showing the polishing pad 16 near the through hole 84at an enlarged scale according to a modification of the eleventhembodiment. The polishing pad 16 is a single-layer pad and is made of awater-absorbent material, e.g., SUBA400 (trade name) or SUBA800 (tradename) manufactured by Rodel, Inc. The inner circumferential surface ofthe through hole 84 is covered by a resin coating 232 for repellingwater.

With this structure, the pure water supplied to the through hole 84hardly seeps into the polishing pad 16, thereby reducing the change inthe polishing characteristics of the polishing pad 16, as with theeleventh embodiment.

In the present embodiment, the inner circumferential surface of thethrough hole 84 has the resin coating 232 for allowing the inner surfaceof the through hole 84 to be water repellent. However, insofar as theinner circumferential surface of the through hole 84 has a waterrepellency, a means for producing a water repellency is not limited tothe resin coating in the present invention. For example, the polishingpad 16 may be made of a water-repellent material. Alternatively, acollar made of a water-repellent material may be mounted in the throughhole 84.

In the present embodiment, although the inner circumferential surface ofthe through hole 84 has a water repellency, it is preferable that theouter circumferential surface of the polishing pad 16 also has a waterrepellency for the following reasons:

The slurry supplied as a polishing abrasive to the polishing pad 16flows outwardly on the polishing pad 16, and further flows on the outercircumferential surface and then drops from the polishing pad 16.Generally, the polishing pad 16 has a surface layer made of a highlywater-repellent material so as to prevent the slurry from seeping intothe polishing pad 16. However, the polishing pad 16 may have awater-absorbent material exposed on the outer circumferential surfacethereof. For example, the two-layer polishing pad has a surface layerpad made of a highly water-repellent material and a lower layer pad madeof a water-absorbent material. With the two-layer polishing pad, thelower layer pad which is water-absorbent is exposed on the outercircumferential surface thereof. If the slurry seeps into thewater-absorbent material on the outer circumferential surface, thepolishing characteristics of the polishing pad 16 tend to change. Inorder to prevent such a trouble, it is preferable to make the outercircumferential surface water repellent. The slurry is thus preventedfrom seeping into the outer circumferential surface of the polishing pad16, thereby reducing the property change of the polishing pad 16.

A substrate polishing apparatus 10 according to a twelfth embodiment ofthe present invention has the same structure as the substrate polishingapparatus 10 according to the first embodiment, but is different in thatthe pipe piece 86 is made of a soft material whose softness issubstantially the same as or higher than that of the polishing pad 16.

Since the pipe piece 86 is made of a soft material whose softness issubstantially the same as or higher than that of the polishing pad 16,the substrate 18 is not damaged even when the pipe piece 86 is broughtinto contact with the substrate 18. Therefore, the outlet portion can bepositioned closer to the substrate 18, and the outlet 88 can bepositioned substantially in the same plane as the polishing surface 90.The pipe piece 86 and the polishing pad 16 may be dressed together, andthe pipe piece 86 may be adjusted in vertical position together with thepolishing pad 16 for thereby easily positioning the outlet 88substantially in the same plane as the polishing surface 90.

FIG. 39 is a view showing a modification of the twelfth embodiment. Inthis modification, a cap 224 made of a soft material whose softness issubstantially the same as or higher than that of the polishing pad 16 ismounted on the pipe piece 86. The cap 224 serves as an outlet portion,and an outlet 226 as an end portion of the cap 224 serves as a supplyport of the measurement fluid to be supplied through the supply passage44 into the through hole 84. The substrate 18 is not damaged even whenthe cap 224 made of a soft material is brought into contact with thesubstrate 18. The cap 224 allows the outlet 226 to be positioned closerto the substrate 18, thus increasing the ability to remove the polishingabrasive from the area where measurement light is applied, which islocated in front of the outlet portion.

In the twelfth embodiment, the pipe piece 86 may be made of the samematerial as the polishing pad 16. With this structure, since thesubstrate 18 is not damaged even when the pipe piece 86 is brought intocontact with the substrate 18, as with the twelfth embodiment, theoutlet portion may be positioned much closer to the substrate 18.

A substrate polishing apparatus 10 according to a thirteenth embodimentof the present invention has the same structure as the substratepolishing apparatus 10 according to the first embodiment, but isdifferent in that the pipe piece 86 serving as the outlet portion ismade of a material whose elastic modulus is larger than that of thepolishing pad 16.

With this structure, the vertical position of the outlet portion can beadjusted by setting a dressing pressure to be higher than a polishingpressure as described below. Specifically, the substrate polishingapparatus 10 dresses the outlet portion together with the polishing pad16. Since the elastic modulus of the outlet portion is larger than theelastic modulus of the polishing pad 16, when the dressing process isfinished and the pressure applied during the dressing process isreleased, the polishing pad 16 extends such that the expansion of thepolishing pad 16 is greater than that of the outlet portion. Therefore,when the dressing process is finished, the outlet portion is retractedinto the through hole 84 of the polishing pad 16. In the substratepolishing apparatus 10, the polishing pressure is set to be smaller thanthe dressing pressure. Consequently, when the substrate 18 is polished,the outlet portion does not project from the polishing surface 90.Specifically, the outlet portion is positioned in the through hole 84 ofthe polishing pad 16 and does not obstruct the polishing process.

A substrate polishing apparatus 10 according to a fourteenth embodimentof the present invention has the same structure as the substratepolishing apparatus 10 according to the first embodiment, but isdifferent in that the supply passage 44 has a mirror inner surface.Although the supply passage 44 may have the mirror inner surfacethroughout its entire length, it is preferable that the supply passage44 has the mirror inner surface only in the vicinity of the outlet 88 ofthe supply passage 44. For example, the pipe piece 86 serving as theoutlet portion may have the mirror inner surface. The mirror innersurface is effective to suppress the absorption of light in the supplypassage 44, and hence the attenuation of measurement light and reflectedlight can be reduced. Accordingly, the amount of the reflected lightthat is received is increased, thus increasing the S/N ratio.

A substrate polishing apparatus 10 according to a fifteenth embodimentof the present invention has the same structure as the substratepolishing apparatus 10 according to the first embodiment, but isdifferent in that the supply passage 44 has a nonreflective innersurface. Although the supply passage 44 may have the nonreflective innersurface throughout its entire length, it is preferable that the supplypassage 44 has the nonreflective inner surface only in the vicinity ofthe outlet 88 of the supply passage 44. For example, the pipe piece 86serving as the outlet portion may have the nonreflective inner surface.The nonreflective inner surface is effective to suppress the reflectionof light in the supply passage 44, and hence wavelength shift due toreflection on the inner surface of the supply passage 44 can be reduced.Accordingly, in the case where a film on the substrate 18 is measuredbased on the wavelength shift, the nonreflective inner surface canincrease the S/N ratio.

Although several embodiments of the substrate polishing apparatusaccording to the present invention have been described above in detail,the present invention is not limited to the above embodiments.

According to the present invention, since the outlet portion of thesupply passage is positioned in the through hole of the polishing pad,the outlet portion of the supply passage is close to the substrate.Therefore, the flow velocity of the fluid supplied from the supplypassage is increased at the outlet portion, and the fluid is vigorouslyejected from the gap between the substrate and the outlet portion towardthe outside of the supply passage, thus forming a flow along thesubstrate. The flow of the fluid can effectively remove the polishingabrasive from the area where measurement light is applied, which islocated in front of the outlet portion.

The entire structures of the substrate polishing apparatus 10 accordingto the embodiments have been described above together with the structureof the sensor 26. Features of the embodiments will be described below.

In the substrate polishing apparatus 10 shown in FIG. 1, the lightsource component of the light source unit 32 is an expendable component.In the present embodiment, the light source component comprises a lamp.If the light source unit 32 comprises a halogen lamp, then the lamp hasa service life of about four months. However, the service life of thelamp differs depending on the type thereof and condition under which thelamp is used. Within the scope of the present invention, the lamp is notlimited to a halogen lamp. For example, a xenon flash lamp may be used.Within the scope of the present invention, the light source component isnot limited to a lamp. For example, an LED or a laser light source maybe used.

In the present embodiment, the supply control valves 58, 60 and thedischarge control valve 62 comprise an electromagnetic valve which isalso expendable component. If the electromagnetic valve is made ofstainless steel, then the electromagnetic valve has a service life ofabout six months (15,000,000 cycles of operation). If theelectromagnetic valve is made of resin, then the electromagnetic valvehas a service life of about four months (10,000,000 cycles ofoperation). However, the service life of the electromagnetic valvediffers depending on the type thereof and condition under which theelectromagnetic valve is used.

Heretofore, these expendable components are mounted on the lower surfaceof the polishing table 12, and cannot easily be replaced. In view ofsuch a drawback, the present embodiment is arranged to allow theexpendable components to be replaced easily. A structure for replacing alamp will be described below. However, the same structure can be appliedfor replacing an electromagnetic valve.

FIGS. 40A and 40B are views showing an expendable component replacementdoor provided on the polishing table of the substrate polishingapparatus shown in FIG. 1. FIG. 40A is a plan view and FIG. 40B is aside view. As shown in FIGS. 40A and 40B, the power supply unit 28, thecontroller unit 30, the light source unit 32, the photometer unit 34,the pump 50, and an electromagnetic valve unit 1074 are arranged alongthe outer edge of the polishing table 12 and are disposed inwardly of askirt 1076. The skirt 1076 has an outer circumferential surface servingas a side surface 1078 of the polishing table 12.

As to a feature of the present embodiment, an expendable componentreplacement door 1080 is provided on the side surface 1078 of thepolishing table 12. The expendable component replacement door 1080 isattached to the side surface 1078 by a hinge 1082. When the expendablecomponent replacement door 1080 is closed, a replacement mouth 1084 iscovered by the expendable component replacement door 1080. Theexpendable component replacement door 1080 is disposed outwardly of thelight source unit 32. The replacement mouth 1084 has a shape that allowsthe light source unit 32 to be taken in and out through the replacementmouth 1084. A grip 1086 is attached to a central portion of theexpendable component replacement door 1080, and bolts 1088 are mountedon respective four corners of the expendable component replacement door1080. When a maintenance operation is not performed, the expendablecomponent replacement door 1080 is fastened to the polishing table 12 bythe bolts 1088. Although not shown, a seal such as an O-ring is providedon the expendable component replacement door 1080 so as to prevent thepolishing slurry and the pure water for measurement from entering. Inorder to achieve a reliable seal, three or more bolts are preferablyprovided. Therefore, in the present embodiment, the four bolts 1088 areprovided.

An operation of replacing the lamp will be described below. Whenreplacing the lamp, the operator removes the bolts 1088 from the fourcorners of the expendable component replacement door 1080. Then, theoperator holds the grip 1086 and opens the expendable componentreplacement door 1080. The operator puts a hand through the replacementmouth 1084 and removes the light source unit 32 from the polishing table12. The light source unit 32 is removed through the replacement mouth1084. The operator replaces the lamp of the light source unit 32. Thelight source unit 32 is inserted through the replacement mouth 1084, andinstalled on the polishing table 12 in a predetermined position. Then,the expendable component replacement door 1080 is closed and the bolts1088 are tightened. The replacement of the lamp is thus finished.

As shown in FIG. 3, the substrate processing apparatus 66 has workingwindows 74 provided on a chamber in which the substrate polishingapparatus 10 is installed. The working windows 74 are originally used toreplace the polishing pad. In the present embodiment, the workingwindows 74 are also used to replace a lamp. Working areas 1100 inside ofthe working windows 74 are used to replace the lamp. The operator opensthe doors of the working windows 74 and manually turns the polishingtable 12 so as to position the expendable component replacement door1080 in the working area 1100. Then, the operator replaces the lampaccording to a process described above.

Preferably, the position where the polishing table 12 is stopped isautomatically controlled for maintenance. For example, when the operatorinputs an instruction of maintenance with an operation panel, thepolishing table 12 is rotated. The polishing table 12 is then stoppedsuch that the expendable component replacement door 1080 is positionedin the working area 1100 of the substrate processing apparatus 66. Thus,the replacing process is further facilitated. The stop control for thepolishing table is performed in response to an input operation made bythe operator. However, the stop control for the polishing table may beautomatically performed at a timing when a certain period of time haspassed after starting of using the expendable component. The same stopcontrol may be performed simultaneously with an alarm signal outputtedwhen failure occurs.

The substrate polishing apparatus according to the present embodimenthas been described in detail above. As described above, the expendablecomponents can be easily replaced by providing the expendable componentreplacement door.

In the above embodiment, the structure for replacing a lamp has beendescribed. However, the same structure can be used to replace anelectromagnetic valve. In this case, the expendable componentreplacement door is disposed in the vicinity of the electromagneticvalve unit. The electromagnetic valve unit is removed, so that theelectromagnetic valve of the electromagnetic valve unit is replaced.This feature is also applicable to other embodiments to be describedbelow.

Within the scope of the present invention, the expendable components arenot limited to the lamp and the electromagnetic valve. As describedabove, the expendable component may be a light source component otherthan the lamp, e.g., an LED or a laser light source. Within the scope ofthe present invention, the expendable component may be replaced togetherwith other component disposed near the expendable component. Forexample, an entire unit including the expendable component may bereplaced. Such an operation is also included in the expendable componentreplacing operation. Within the scope of the present invention, further,a process of determining whether a film is present or not may beincluded in the process of measuring a film thickness. Furthermore, aprocess of measuring a film is not limited to the process of measuring afilm thickness.

Within the scope of the present invention, the measurement fluid is notlimited to a liquid, and may be a gas, e.g., air. Within the scope ofthe present invention, the substrate measuring device is not limited tothe optical-type device as described above. The substrate measuringdevice may be an eddy-current-type device, for example. Theeddy-current-type device may be used to determine an end point. In thiscase also, the replacement of an expendable component can befacilitated.

FIGS. 41A and 41B show a modification of the above embodiment. FIG. 41Ais a plan view and FIG. 41B is a side view. In this modification, anexpendable component replacement door 1102 is slidable along the sidesurface 1078 of the polishing table 12. Thus, the expendable componentreplacement door 1102 is opened and closed in a sliding motion. When theexpendable component replacement door 1102 is opened, an expendablecomponent is taken in or out through a replacement mouth 1104. Theexpendable component replacement door 1102 has four corners which arefastened to the polishing table 12 by bolts 1106. The bolts 1106 areremoved when the replacement operation is performed.

FIGS. 42A and 42B show another modification of the above embodiment.FIG. 42A is a plan view and FIG. 42B is a side view. In thismodification, an expendable component replacement door 1108 comprises acover which can be removed from the polishing table 12. The cover isalso included in the expendable component replacement door according tothe present invention. The expendable component replacement door 1108 isfastened to the polishing table 12 by bolts 1110 at respective fourcorners. A grip 1112 is attached to the expendable component replacementdoor 1108.

Preferably, retaining rings are combined with the bolts 1110 so as toprevent the bolts 1110 from being completely detached from the fourcorners of the expendable component replacement door 1108. With thisstructure, when the bolts 1110 are loosened, the bolts 1110 stay inpositions in such a state that the bolts 1110 project from theexpendable component replacement door 1108. The bolts 1110 can be thusused as a grip for removing and installing the expendable componentreplacement door 1108. Therefore, it is possible to dispense with thegrip 1112.

FIGS. 43A and 43B show still another modification. FIG. 43A is a planview and FIG. 43B is a side view. In this modification, the light sourceunit 32 is mounted on a drawer member 1116. In the present embodiment,the drawer member 1116 comprises a plate with the light source unit 32mounted thereon. A guide mechanism 1118 is provided for allowing thedrawer member 1116 to slide outwardly of the polishing table 12. Anexpendable component replacement door 1120 is attached to the drawermember 1116.

In an operation for replacing the expendable component, the operatorpulls a grip 1122 of the expendable component replacement door 1120 soas to pull the light source unit 32 together with the drawer member 1116out of the polishing table 12. Then, the operator replaces the lamp ofthe light source unit 32. This structure can further facilitate thereplacement of the expendable component.

The above drawer mechanism is also applicable to the structures shown inFIGS. 40A and 40B, or FIGS. 41A and 41B. In these cases, the drawermember and the expendable component replacement door may be separatefrom each other.

FIG. 44 shows still another modification. In this modification, theexpendable component replacement door is mounted on the surface of thepolishing table 12 against which the substrate is pressed. Specifically,as shown in FIG. 44, an expendable component replacement door 1124 ismounted on the polishing surface 90 of the polishing table 12. Morespecifically, the expendable component replacement door 1124 is mountedon a table surface (rotational surface) below the polishing pad 16 whichhas the polishing surface 90. In order to illustrate in aneasy-to-understand way, the expendable component replacement door 1124is indicated by the solid line in FIG. 44. Actually, the expendablecomponent replacement door 1124 is concealed below the polishing pad 16in FIG. 44. The expendable component replacement door 1124 is disposeddownwardly of a central region of the polishing surface 90, and is thusdeviated from the orbit of the substrate.

The expendable component replacement door 1124 is constructed to providea flat surface in cooperation with the table surface surrounding theexpendable component replacement door 1124. Thus, defect due to a stepon the polishing surface 90 is prevented from occurring.

Another embodiment of the present invention will be described below.This embodiment is provided for facilitating the replacing operation ofan expendable component by switching a plurality of expendablecomponents.

Referring to FIG. 45, the polishing table 12 of the substrate polishingapparatus 10 according to the present embodiment has the power supplyunit 28, the controller unit 30, the light source unit 32, thephotometer unit 34, the electromagnetic valve unit 1074, and the pump50, as with the above embodiment. The light source unit 32 has a lamp,and the electromagnetic valve unit 1074 has an electromagnetic valvedisposed in the supply passage and the discharge passage for themeasurement fluid.

The polishing table 12 has a spare light source unit 1142 and a spareelectromagnetic valve unit 1144. The spare light source unit 1142 hasthe same structure as the light source unit 32, and is capable ofsupplying measurement light to the sensor, as with the light source unit32. The spare electromagnetic valve unit 1144 has the same structure asthe electromagnetic valve unit 1074, and is disposed in the supplypassage and the discharge passage for the measurement fluid, as with theelectromagnetic valve unit 1074.

The controller unit 30 functions as an expendable component switchingmeans according to the present invention in the following manner. First,a function for switching from the light source unit 32 to the sparelight source unit 1142 will be described below.

The controller unit 30 monitors a usage situation of the light sourceunit 32, and functions as a usage situation monitoring mechanism ordetector. In the present embodiment, a usage period is monitored as theusage situation. The controller unit 30 stores a lamp switchingcriterion period that has been set in accordance with the service lifeof the lamp of the light source unit 32. The lamp switching criterionperiod is four months, for example. The controller unit 30 determineswhether or not the usage period of the light source unit 32 has reachedthe lamp switching criterion period.

If the usage period has reached the lamp switching criterion period,then the controller unit 30 instructs the light source unit 32 to beturned off, and instructs the spare light source unit 1142 to be turnedon. In a subsequent measuring process, the light source unit 32 is notturned on, but the spare light source unit 1142 is turned on.

An operation of switching from the electromagnetic valve unit 1074 tothe spare electromagnetic valve unit 1144 will be described below. Thecontroller unit 30 also monitors a usage period as a usage situation ofthe electromagnetic valve unit 1074. The controller 30 stores a valveswitching criterion period that has been set in accordance with theservice life of the electromagnetic valve of the electromagnetic valveunit 1074. The valve switching criterion period is six months, forexample. The controller unit 30 determines whether or not the usageperiod of the electromagnetic valve unit 1074 has reached the valveswitching criterion period.

When the usage period has reached the valve switching criterion period,the controller unit 30 stops instructing the electromagnetic valve unit1074 to open and close the valve thereof, and instructs the spareelectromagnetic valve unit 1144 to open and close the valve thereof. Ina subsequent measuring process, the electromagnetic valve unit 1074 doesnot function for measurement, but alternatively, the spareelectromagnetic valve unit 1144 functions for measurement.

As described above, in the present embodiment, the plurality ofexpendable components having the same function are provided. Theexpendable component, of those expendable components, which functionsfor measuring a film is switched to other component. Therefore, it ispossible to reduce the number of times the expendable component isreplaced, thus reducing the burden on the operator.

In the present embodiment, the expendable component is automaticallyswitched based on the usage situation of the expendable component whichfunctions for measuring a film. Consequently, it is possible to reduce awork that the operator has to perform, thus further reducing the burdenon the operator.

In the present embodiment, when the expendable component is consumed orbreaks down, it is not necessary to shut off the substrate polishingapparatus immediately to perform the replacing operation. The expendablecomponent may be replaced during other maintenance operation such asreplacing the polishing pad. Therefore, an operating rate of thesubstrate polishing apparatus can be increased.

In the present embodiment, first, the expendable component iscontinuously used, and thereafter the spare expendable component isused. However, the present invention is not limited to such a manner. Aplurality of the expendable components may be used alternately. In thiscase, a switching period may be set to be shorter than the service lifeof the expendable component.

In the present embodiment, the usage period is monitored as the usagesituation. However, the present invention is not limited to such anexample. A diagnostic device for diagnosing a failure or a service lifeof the expendable component may be provided. A sensor signal fordiagnosis is processed in the controller unit or the like, and then adiagnostic result is obtained. The expendable component is automaticallyswitched based on the diagnostic result. A failure or the like isindicated by an alarm so as to prompt the operator to replace theexpendable component.

The present embodiment may be combined with the embodiment shown inFIGS. 40A and 40B. In this case, the expendable component replacementdoor is disposed on the polishing table, and a plurality of theexpendable components having the same function are disposed in thepolishing table. These expendable components are switched or replacedthrough the expendable component replacement door. Thus, the number oftimes the expendable components are replaced is reduced, and theoperation for replacing the expendable components is facilitated. As aresult, the entire replacing operation is further facilitated.

Still another embodiment of the present invention will be describedbelow. In this embodiment, the expendable component is disposed outsideof the polishing table so as to facilitate the replacing operation, asdescribed below.

FIG. 46 shows a substrate polishing apparatus having the expendablecomponent disposed outside of the polishing table. A substrate polishingapparatus 1150 shown in FIG. 46 differs from the substrate polishingapparatus 10 shown in FIG. I in that a light source unit is not mountedon the polishing table 12. Alternatively, a light source unit 1152 isdisposed outside of the polishing table 12. In the present embodiment,an area outside of the polishing table 12 is an area outside of a spaceoccupied by the polishing table 12, i.e., a space occupied by thepolishing table 12 and the mounted components. More specifically, thearea outside of the polishing table 12 is an area outside of a spacedefined by the upper surface and the side surface (skirt) of thepolishing table 12. The light source unit 1152 is disposed in a suitablelocation where the lamp can be easily replaced.

In order to guide light emitted by the lamp of the light source unit1152 to the sensor 26, a fixed-side light guide 1154 is disposed outsideof the polishing table 12, and a rotary-side light guide 1156 isdisposed in the polishing table 12. The rotary-side light guide 1156 isconnected to the sensor 26. Each of the fixed-side light guide 1154 andthe rotary-side light guide 1156 comprises an optical fiber.

The fixed-side light guide 1154 and the rotary-side light guide 1156 areconnected to each other by an optical rotary joint 1158. The opticalrotary joint 1158, the electric rotary connector 36, and the fluidrotary joint 48 are mounted on a shaft of the polishing table 12 forthereby transmitting light from the fixed-side light guide 1154 to therotary-side light guide 1156. The optical rotary joint 1158, theelectric rotary connector 36, and the fluid rotary joint 48 mayalternatively be disposed in a location other than the shaft of thepolishing table 12, e.g., on the outer circumferential surface of thepolishing table 12 or on the lower portion of the polishing table 12.

The substrate polishing apparatus 1150 is different from the substratepolishing apparatus 10 shown in FIG. 1 in that a supply control valve isnot provided in the polishing table 12. Alternatively, the substratepolishing apparatus 1150 has supply control valves 1160, 1162 disposedoutside of the polishing table 12. As already described, the supplycontrol valves 1160, 1162 are used to switch ejection of the measurementfluid and low-flow-rate supply of the measurement fluid.

More specifically, a supply passage 1164 for the measurement fluidcomprises a rotary-side supply passage 1166 and a fixed-side supplypassage 1168. The rotary-side supply passage 1166 is disposed in thepolishing table 12, and the fixed-side supply passage 1168 is disposedoutside of the polishing table 12. The rotary-side supply passage 1166and the fixed-side supply passage 1168 are connected to each other bythe rotary joint 48.

The substrate polishing apparatus 1150 also has the same mechanism fordischarging the measurement fluid. Specifically, unlike the substratepolishing apparatus 10 shown in FIG. 1, the substrate polishingapparatus 1150 does not have a discharge control valve in the polishingtable 12. Alternatively, a discharge control valve 1170 is providedoutside of the polishing table 12.

In order to allow the discharge control valve 1170 to be positionedoutside of the polishing table 12, a discharge passage 1172 extendsoutwardly from the polishing table 12. The discharge passage 1172comprises a rotary discharge passage 1174 disposed in the polishingtable 12 and a fixed discharge passage 1176 disposed outside of thepolishing table 12. The rotary discharge passage 1174 and the fixeddischarge passage 1176 are connected to each other by the rotary joint48. The discharge control valve 1170 is disposed in the fixed dischargepassage 1176. The pump 50 for forcibly discharging the measurement fluidis also disposed outside of the polishing table 12 and is connected tothe fixed discharge passage 1176.

The above supply control valves 1160, 1162 and the discharge controlvalve 1170 constitute an electromagnetic valve unit. The electromagneticvalve unit is disposed outside of the polishing table 12 in the samemanner as described above. The electromagnetic valve unit is disposed ina suitable location where the valves can be easily replaced.

An operation of replacing the expendable components according to thepresent embodiment will be described below. The expendable componentsare a lamp and electromagnetic valves. At the time of replacement, theoperator opens a working door provided on the wall of the substrateprocessing apparatus. The operator puts a hand through the door andreplaces the expendable components.

According to the present embodiment, as described above, since theexpendable components are disposed outside of the polishing table 12,the expendable components can be replaced easily.

FIG. 47 shows an example of the optical rotary joint 1158 incorporatedin the substrate polishing apparatus 1150 shown in FIG. 46.

In FIG. 47, each of the fixed-side light guide 1154 and the rotary-sidelight guide 1156 comprises an optical fiber. The rotary-side light guide1156 extends along a rotational axis Y of the polishing table 12. Thefixed-side light guide 1154 extends perpendicularly to the rotationalaxis Y, and an extension X of the rotary-side light guide 1156 crossesthe rotational axis Y. In FIG. 47, an end portion of the fixed-sidelight guide 1154 constitutes a fixed-side end portion 1178, and an endportion of the rotary-side light guide 1156 constitutes a rotary-sideend portion 1180 which is positioned at a lower end of the polishingtable 12.

A mirror 1182 is disposed on the rotational axis Y. As shown in FIG. 47,the mirror 1182 is disposed such that the rotary-side end portion 1180and the fixed-side end portion 1178 face each other through the mirror1182. With this arrangement, light is emitted from the fixed-side lightguide 1154, reflected by the mirror 1182, enters the rotary-side lightguide 1156, and is transmitted to the non-illustrated sensor.

With the arrangement shown in FIG. 47, the light is continuouslytransmitted from the fixed side to the rotary side during the polishingtable 12 is rotated. The mirror 1182 may be a plane mirror or a concavemirror. As a modification of FIG. 47, the fixed-side light guide 1154may be bent instead of providing the mirror 1182. Specifically, theoptical fiber constituting the fixed-side light guide 1154 may be bentupwardly so as to allow the fixed-side end portion 1178 to face therotary-side end portion 1180. This modified structure also allows lightto be transmitted appropriately.

FIG. 48 shows another example of the optical rotary joint. In FIG. 48,the rotary-side light guide 1156 is bent at a right angle in thepolishing table 12. The rotary-side end portion 1180 is thus positionedat a side surface 1186 of a shaft 1184 of the polishing table 12. Thefixed-side light guide 1154 is disposed such that the rotary-side endportion 1180 and the fixed-side end portion 1178 face each other.

FIGS. 49A and 49B are cross-sectional views taken along line A-A of FIG.48. As indicated by the illustrated arrow, since the polishing table 21is rotated, the rotary-side end portion 1180 and the fixed-side endportion 1178 face each other in a predetermined light guiding regionextending in the rotating direction of the polishing table 12. The lightguiding region ranges from a position where the fixed-side end portion1178 and the rotary-side end portion 1180 start facing each other to aposition where such facing ends.

FIGS. 50A, 50B, and 50C show modifications of FIGS. 49A and 49B in whichthe light guiding region is increased. In FIG. 50A, the rotary-side endportion 1180 is widened in the circumferential direction. In FIGS. 50Band 50C, the fixed-side end portion 1178 is widened. With thesestructures, the fixed-side end portion 1178 and the rotary-side endportion 1180 can face each other in an increased range.

The above light guiding region is preferably set so as to include anangular position of the polishing table where the substrate is in themeasurement position. It is appropriate to measure the substrate atseveral times while the substrate passes over the sensor on the polishedsurface. In this case, the light guiding region is set to allow thefixed-side end portion 1178 and the rotary-side end portion 1180 to faceeach other while all the measuring points of the substrate pass over thesensor. The light guiding region may be set to allow the fixed-side endportion 1178 and the rotary-side end portion 1180 to face each otherthroughout the entire period of time when the substrate passes over thesensor.

The preferred optical rotary joints according to the present embodimentshave been described above. With the above structures, since the endportions of the rotary-side and fixed-side light guides are not requiredto communicate with each other at all times, the structure fortransmitting light becomes simple. For example, it is possible todispense with the mirror unlike the structure shown in FIG. 47, and theend portions of the light guide can be positioned more freely.

A preferred example of the rotary joint 48 which is used to supply themeasurement fluid and incorporated in the substrate polishing apparatus1150 shown in FIG. 46 will be described below.

FIGS. 51A and 51B show a rotary joint 1200 according to the presentembodiment. The rotary joint 1200 is used to supply the measurementfluid such as pure water.

The rotary joint 1200 has a cylindrical housing 1202, and a rotor 1204is housed the housing 1202. The rotor 1204 is mounted on the polishingtable (not shown) of the substrate polishing apparatus, and is rotatableabout the rotational axis of the polishing table. Since such an elementis mounted on the polishing table and is rotated with the polishingtable, the rotor 1204 constitutes the polishing table in the presentinvention.

The rotor 1204 has a rotary-side supply passage 1206 formed therein, andthe housing 1202 has a fixed-side supply passage 1208 formed therein.The rotary-side supply passage 1206 and the fixed-side supply passage1208 have a circular cross section and have the same cross sectionalarea as each other. The rotary-side supply passage 1206 extends alongthe rotational axis of the rotor 1204 to the sensor at the polishingsurface of the polishing table. A lower portion of the rotary-sidesupply passage 1206 is bent at a right angle.

An end portion of the rotary-side supply passage 1206 constitutes arotary-side end portion 1210, and an end portion of the fixed-sidesupply passage 1208 constitutes a fixed-side end portion 1212. Therotary-side end portion 1210 is positioned at an outer circumferentialsurface 1214 of the rotor 1204, and the fixed-side end portion 1212 ispositioned at an inner circumferential surface 1216 of the housing 1202.As shown in the drawing, the fixed-side end portion 1212 comprises asupply groove 1218 extending in the circumferential direction. Aposition and a shape of the supply groove 1218 are set such that thefixed-side end portion 1212 and the rotary-side end portion 1210 faceeach other in a suitable range.

The inner circumferential surface 1216 of the housing 1202 is disposedclosely to the outer circumferential surface 1214 of the rotor 1204 in aregion where the fixed-side end portion 1212 is not provided. An orificegap 1220 is formed between the outer circumferential surface 1214 of therotor 1204 and the inner circumferential surface 1216 of the housing1202. The housing 1202 and the inner circumferential surface 1216thereof correspond to an orifice forming member and an orifice formingsurface, respectively, according to the present invention.

Seals 1222 for preventing the measurement fluid from leaking aredisposed between the inner circumferential surface 1216 of the housing1202 and the outer circumferential surface 1214 of the rotor 1204. Therotary-side supply passage 1206 and the fixed-side supply passage 1208are disposed between the two seals 1222.

FIG. 52 is a view illustrating an appropriate position and shape of thesupply groove 1218 of the fixed-side end portion 212. When the polishingtable 12 is rotated, the substrate 18 moves relatively to the polishingtable 12. At this time, the substrate 18 traces a circular orbit on thepolishing table 12. When an angular position of the polishing table 12in the rotating direction is in an overlapping region 1224, thesubstrate 18 is positioned above the sensor 26 provided on the polishingsurface for a certain period. Such a period is set as a predeterminedconduction period in the present embodiment. The shape of the supplygroove 1218 is formed so as to allow the rotary-side end portion 1210and the fixed-side end portion 1212 to face each other in the conductionperiod.

More specifically, a start point 1226 and an end point 1228 of thesupply groove 1218 are set to correspond to respective positions (pointsC, D) of the rotary-side end portion 1210 where the substrate 18 reachesthe sensor 26 and leaves the sensor 26.

An operation of the rotary joint 1200 shown in FIGS. 51A and 51B will bedescribed below. When the rotary joint 1200 is rotated, the fixed-sideend portion 1212 of the fixed-side supply passage 1208 and therotary-side end portion 1210 of the rotary-side supply passage 1206 faceeach other to form a relatively large opening during the aboveconduction period, i.e., a period in which the sensor 26 is covered bythe substrate 18. Therefore, a large amount of the measurement fluid issupplied to the sensor 26 and is ejected in the sensor 26.

On the other hand, in a period other than the conduction period, thefixed-side end portion 1212 and the rotary-side end portion 1210 do notface each other. The fixed-side end portion 1212 and the rotary-side endportion 1210 are connected to each other through the orifice gap 1220.Since the flow passage is narrow, the measurement fluid is supplied tothe sensor 26 at a low flow rate. Therefore, when the sensor 26 is notcovered by the substrate 18, a large amount of the measurement fluid isprevented from being ejected to the polishing table 12, thus preventingthe slurry on the polishing table 12 from being diluted.

According to the present embodiment, as described above, the measurementfluid can be delivered with a relatively simple structure. Further,since the orifice gap is provided, a small amount of the measurementfluid is delivered when the end portions of the fluid passages do notface each other.

According to the present embodiment, as described above, a switchingcontrol of the flow rate of the measurement fluid can be realized by asimple structure of a fluid delivering mechanism. Thus, it is possibleto dispense with the electromagnetic valve for controlling the flow rateof the measurement fluid. Even if the electromagnetic valve remainsinstalled, the service life of the electromagnetic valve is greatlyincreased because the electromagnetic valve do not have to be operatedfrequently during the measurement. It is thus possible to eliminate theoperation of replacing the electromagnetic valve.

The structure of the fluid supply side has been described above.However, the same structure may be applied to the fluid discharge side.When discharging the measurement fluid, a compulsory discharge may beswitched by the rotary joint. In this case, a gap between the rotor ofthe rotary joint and the housing may be very small to substantiallyeliminate the orifice gap. In this manner, the present invention isapplicable to both the fluid supply side and the fluid discharge side.

FIG. 53 shows a modification of the present embodiment. In theembodiment shown in FIGS. 51A and 51B, the supply groove 1218 is formedin the fixed-side end portion 1212 of the fixed-side supply passage1208. In FIG. 53, the rotary-side end portion 1210 of the rotary-sidesupply passage 1206 is widened. This structure can perform the samefunction as the above supply groove.

FIGS. 54A and 54B show another embodiment. A rotary joint 1230 has arotor 1232 and a base 1234. The rotor 1232 and the base 1234 have arotary-side supply passage 1236 and a fixed-side supply passage 1238,respectively.

The rotor 1232 and the base 1234 have respective delivering surfaces1242, 1244 perpendicular to a rotational axis 1240 of the rotor 1232.The rotary-side supply passage 1236 and the fixed-side supply passage1238 have a rotary-side end portion 1246 and a fixed-side end portion1248, respectively, which are positioned at the delivering surfaces1242, 1244, respectively. An orifice gap 1259 is formed between thedelivering surfaces 1242, 1244. Although the orifice gap 1259 is shownexaggeratedly in order to illustrate in an easy-to-understand way, theorifice gap 1259 is actually very small. The fixed-side end portion 1248has a supply groove 1250 formed on the delivering surface 1244 of thebase 1234. The supply groove 1250 extends along an arc whose center ispositioned on the rotational axis 1240. Although not shown, a housinghaving a leakage-prevention seal mechanism is disposed on outercircumferential surfaces of the rotor 1232 and the base 1234.

When the rotor 1232 is rotated, the rotary-side end portion 1246 of therotary-side supply passage 1236 and the fixed-side end portion 1248 ofthe fixed-side supply passage 1238 face each other to increase the flowrate during a period in which the rotary-side end portion 1246 passesover the supply groove 1250. In the other period, the orifice gap 1259is formed between the fixed-side supply passage 1238 and the rotary-sidesupply passage 1236, thus lowering the flow rate. Therefore, with thisstructure, the same function as the above embodiment can be obtained. Inthis manner, within the scope of the present invention, the fluid maynot be delivered through the cylindrical surfaces. The above supplygroove may be formed in the rotor.

Although preferred embodiments of the present invention have beendescribed above, the embodiments may be modified by those skilled in theart within the scope of the present invention. For example, theexpendable components are not limited to the light source component andthe control valve, as already described.

According to the present invention, the expendable component can betaken in and out through the expendable component replacement door, andhence the expendable component can be replaced easily.

According to the present invention, a plurality of the expendablecomponents are provided and switched for reducing the number of timesthe expendable components are replaced.

According to the present invention, the expendable components aredisposed outside of the polishing table, and hence the expendablecomponents can be replaced easily.

According to the present invention, because the structure for deliveringthe fluid to the polishing table allows the flow rate to be adjusted andcontrolled, a valve unit for adjusting the flow rate can be eliminated.

Structural feature of the present embodiment will be described below. Inthe embodiment, a fluid container 2100 (FIG. 1) stores a solvent of theslurry as the measurement fluid. The solvent of the slurry is preferablya main component solvent which is of the same type and has the sameconcentration as the slurry. The solvent is delivered by a supply pump2102 and supplied to the sensor 26 through the supply passage 44.

FIG. 55 is a view showing an example of the sensor incorporated in thesubstrate polishing apparatus shown in FIG. 1.

As shown in FIG. 55, the solvent is ejected into a through hole 2068formed in a polishing pad 2018. The solvent serves to dilute the slurrythat flows from a gap between a polishing table 2012 and a substrate2020 into the through hole 2068. The solvent also serves to clean theslurry attached to the substrate 2020. In this manner, the influencethat the slurry has on measurement is reduced, thus achieving a requiredmeasuring capability.

When a large amount of the solvent serving as a measurement fluid issupplied to the through hole 2068, the solvent tends to flow out fromthe through hole 2068 into the gap between the substrate 2020 and thepolishing table 2012.

However, even if the solvent flows out from the through hole 2068, sincethe solvent is used as the measurement fluid in the present embodiment,an adverse influence on the polishing capability is small, as describedbelow. Specifically, when the solvent flows out, the solvent of theslurry is increased, and the concentration of the abrasive particlesserving as a solute is decreased. However, even if the solvent isincreased, the adverse influence on the polishing capability is small.In particular, the adverse influence that the increased solvent has onthe polishing capability is much smaller than the case where the slurryis diluted by water.

According to the present embodiment, since the solvent of the slurry issupplied as the measurement fluid, even if the measurement fluid flowsout onto the polishing table and is mixed with the slurry, the influencethat the diluted slurry has on the polishing capability can be reduced.The present embodiment is based on the fact that even if the slurry hasa low transparency, the transparency of the slurry solvent which doesnot contain abrasive particles is relatively high. The measuringcapability is maintained by using the solvent of the slurry, and theinfluence that the measurement fluid has on the polishing capability isreduced.

An example of suitable combination of the slurry and the solvent will bedescribed below. In this example, a silica slurry is supplied from aslurry container to polish a silicon oxide film (SiO₂). This kind ofsilica slurry contains an alkaline solvent (pH 10-11) for securing aremoval rate. Therefore, the alkaline solvent is used as a measurementfluid. Accordingly, the influence that the measurement fluid has on theremoval rate when the measurement fluid flows out can be reduced. Thealkaline solvent comprises KOH or NH₄OH, for example.

According to another example, a ceria slurry is supplied to polish asilicon oxide film (SiO₂) or an STI wafer. The ceria slurry contains asurface-active agent solution as a solvent for keeping a low removalrate and securing step characteristics. Therefore, the surface-activeagent solution is used as the measurement fluid. Accordingly, theremoval rate is prevented from being increased and the stepcharacteristics are prevented from being lowered, thus reducing theinfluence on the polishing capability.

The surface-active agent is preferably a cationic surface-active agent.Ceria particles (ceria abrasive particles) of the ceria slurry have aproperty such that the ceria particles easily absorb light. From theviewpoint of zeta potential, since the ceria particles have anequipotential point of about pH 7, the ceria particles are liable to beelectrically attracted to the substrate surface (SiO₂) in pure water.However, if a cationic surface-active agent of less than pH 7 is ejectedto the substrate surface, then the cationic surface-active agent isattracted to the ceria particles and the substrate surface, and hencethey are electrically repelled from each other. Therefore, the ceriaparticles tend to be removed from the substrate surface. In this manner,since the ceria particles on the substrate surface are reduced, morereflected light is received. Therefore, the S/N ratio of the emitted andreceived light is improved, and hence the measuring capability can beincreased.

The slurry and the solvent according to the present invention are notlimited to those described above. For example, in the case where aslurry for polishing a metal film is used, a solvent which is of thesame type and has the same concentration as a solvent contained in sucha slurry is used. The solvent mainly contains an oxidizing agent, achelating agent, and an anticorrosive agent.

In the present embodiment, within the scope of the present invention,the solvent supplied from the supply container does not required to bestrictly the same as the solvent contained in the slurry supplied fromthe slurry container. Specifically, the solvent of the slurry used asthe measurement fluid is not required to be completely the same as theslurry used for polishing the substrate. Insofar as the influence on thepolishing capability or the like is prevented from occurring, thesolvent may have a slightly different concentration, and a solvent of asuitably different type may be employed.

In the present embodiment, it is preferable to apply the followingstructure: A member constituting the supply passage 2042 is made of ahighly chemical-resistant material. A member constituting the dischargepassage 2044 is also made of the same material. For example, thesemembers are made of a resin or a ceramic. The supply passage may becoated with a highly chemical-resistant material, and this structure isincluded in the above structure. With this structure, the supply passagemember is prevented from being damaged by the solvent which is used asthe measurement fluid. Further, the substrate is prevented from beingcontaminated by impurity which has been eluted from the supply passagemember due to the effect of the solvent. It is preferable that theoptical fiber for guiding measurement light and reflected light has thesame structure.

Another embodiment of the present invention will be described below. Asubstrate polishing apparatus according to this embodiment has the samestructure as the embodiments shown in FIGS. 1 through 54. However, thepresent embodiment differs from those embodiments in measurement fluid.

In the present embodiment, the fluid container 2100 contains a highlyviscous fluid which is more viscous than the polishing slurry. Thehighly viscous fluid is delivered by the supply pump 2102 and suppliedto the sensor 26 through the supply passage 2042.

The highly viscous fluid is ejected into the through hole 2068 (see FIG.55) in the polishing pad 2018, so that the through hole 2068 is filledwith the highly viscous fluid. The highly viscous fluid serves to dilutethe slurry that flows into the through hole 2068 from a gap between thepolishing table 12 and the substrate 2020. The highly viscous fluid alsoserves to clean the slurry attached to the substrate 2020. In thismanner, the influence that the slurry has on measurement is reduced,thus achieving a required measuring capability.

A diffusion of the slurry flowing into the through hole is reduced byusing the highly viscous fluid which is more viscous than the slurry.Therefore, the influence that the slurry has on film measurement isreduced, thus increasing the measuring capability.

In the present embodiment, since the highly viscous fluid is used as themeasurement fluid, an amount of the measurement fluid that flows intothe gap between the polishing table 2012 and the substrate 2020 can bereduced. Further, because the above diffusion reducing advantage can beobtained, the same measuring capability can be obtained even if anamount of the highly viscous fluid to be supplied is smaller than thatof water which has been usually used. Thus, the amount of themeasurement fluid flowing out can be reduced. Since the amount of themeasurement fluid flowing out is reduced, the influence that themeasurement fluid has on the polishing capability can be reduced. In thepresent embodiment also, therefore, the measuring capability ismaintained and the influence that the measurement fluid has on thepolishing capability is reduced.

The highly viscous fluid that is applicable to the present embodiment isethylene glycol, for example. Whereas the slurry generally has aviscosity of about 2 cp, ethylene glycol has a viscosity of 23.5 cp at20 degrees Celsius. That is, the viscosity of ethylene glycol is higherthan that of the slurry. In particular, ethylene glycol has a refractiveindex similar to glass, and is suitable for optical measurement in thepresent embodiment. The highly viscous fluid may alternatively beglycerin. Glycerin has a viscosity of 1499 cp at 20 degrees Celsius.Further alternatively, the highly viscous fluid may be a thickener suchas propylene glycol.

The highly viscous fluid may be a solution of the solvent diluted bypure water. The highly viscous fluid is not limited to liquid, but maybe sol or the like. In the present invention, gel may be included in thehighly viscous fluid.

According to the present embodiment, as described above, since thehighly viscous fluid is supplied, the amount of the fluid that flows outis small. Therefore, it may be possible to dispense with a structure fordischarging the fluid. Depending on the type of highly viscous fluid,the compulsory discharge with use of the discharge pump may not beperformed, and the discharge passage may be eliminated.

Still another embodiment of the present invention will be describedbelow. The substrate polishing apparatus according to this embodiment isdifferent from the above embodiment in a measurement fluid.

In the present embodiment, the supply passage 2042 serving as a fluidsupply device forcibly supplies a gas as a measurement fluid. Themeasurement gas comprises air, nitrogen, or a noble gas, for example.The gas may be supplied from a pipe provided in the substrate processingapparatus through the rotary joint 48 to the supply passage 2042. Inthis case, the fluid container 2100 and the supply pump 2102 shown inFIG. 1 are eliminated, and a tank and a pump of the substrate processingapparatus are employed. However, the fluid container 2100 and the supplypump 2102 shown in FIG. 1 may be disposed in the vicinity of thesubstrate polishing apparatus. In this case, a container and a pump forthe gas are provided. It may also be possible to dispense with the pump50 for discharging. The supply and discharge sections are not limited tothe above structure, but may suitably be arranged according to the typeof gas. The gas to be supplied in the present embodiment is a gas whosehumidity, pressure, and contamination are managed.

As already described, in the proposed conventional stream-type measuringdevice, a liquid is forcibly supplied as a measurement fluid, andusually comprises pure water (DIW). The liquid removes the slurry toreduce the influence that the slurry has on measurement. However, sincethe slurry and the liquid are mixed with each other to a certain extent,the influence that the slurry has on measurement still exists, thuscausing the measurement accuracy to be lowered.

In the present embodiment, it is proposed to use the gas as themeasurement fluid, unlike the above prior art. The supplied gas blowsthe slurry from the measuring area and substantially removes the slurry,thus allowing highly accurate measurement to be performed.

According to the present embodiment, even when the gas flows out, thegas does not dilute the slurry, thereby reducing the influence on thepolishing capability. From the viewpoint of this, in the presentembodiment, the measuring capability is maintained and the influencethat the measurement fluid has on the polishing capability is alsoreduced.

In the present embodiment, the measurement fluid is not a liquid.Therefore, the measurement accuracy may be adversely affected by theslurry attached to the light-emitting member and the light-receivingmember. However, the present embodiment can prevent the slurry frombeing attached with use of the following structure:

In the present embodiment, preferably, a water repellent optical fiberis used as a light-emitting optical fiber 2070 and a light-receivingoptical fiber 2072 (FIG. 55), respectively. The light-emitting opticalfiber 2070 and the light-receiving optical fiber 2072 are thus made of awater-repellent material. At least tip end portion of the optical fiber,particularly a portion positioned in the supply passage 2042, may bewater repellent.

The light-emitting optical fiber 2070 is an optical fiber for emittingmeasurement light, and the light-receiving optical fiber 2072 is anoptical fiber for receiving reflected light. Since these optical fibershave a water repellency, any slurry that is attached thereto can beeasily removed.

The supply passage 2042, the discharge passage 2044, or inner surfacesthereof may be made of a water-repellent material or may be coated witha water-repellent material so as to prevent the slurry from beingattached thereto and also prevent the supply passage 2042 and thedischarge passage 2044 from being clogged by the slurry. The secondaryattachment of the slurry from the supply passage 2042 or the like to thelight-emitting optical fiber 2070 and the light-receiving optical fiber2072 is also prevented from occurring.

In the substrate polishing apparatus according to the presentembodiment, the supply of the fluid may be controlled in the mannerdescribed below. The supply of the fluid is controlled before thepolishing process is started.

Pure water is supplied as a cleaning fluid intermittently orcontinuously from the supply passage 2042 to the discharge passage 2044after a preceding substrate is polished or the polishing pad is dressedand just before a next substrate is polished. As described in the aboveembodiment, a gas is supplied as the measurement fluid during thepolishing process. A supply of the cleaning fluid may be started at asuitable time before or after the preceding substrate is polished, orbefore or after the dressing process is finished. The cleaning fluid maybe supplied until several seconds have passed from the start of thepolishing process. Specifically, the cleaning fluid should be suppliedfrom the fluid supply device by utilizing a period of time before thepolishing process is performed.

Since the fluid is supplied in the above manner, an area around thesensor 26 (FIG. 1) can be kept highly clean before measurement isperformed during the polishing process. When a gas is supplied as themeasurement fluid during the polishing process, an excellent measuringcapability can be maintained, and the influence that the measurementfluid has on the polishing capability can be small. The above control isparticularly effective in the polishing process after the dressingprocess because a foreign substance that is produced by the dressingprocess can be removed effectively.

In the above fluid control, a combination of the cleaning fluid and themeasurement fluid may be changed. The cleaning fluid may be pure wateror any of various fluids mentioned in the above embodiments, i.e., theslurry solvent, the highly viscous fluid, or the gas. The measurementfluid may also be the slurry solvent, the highly viscous fluid, or thegas. The cleaning fluid and the measurement fluid may be the same aseach other or may be different from each other. In order to supply thefluid to be used, equipment such as pipe suitable for the fluid isprovided in the polishing table. As described above, even if thecombination of the cleaning fluid and the measurement fluid is changed,the same advantage can be obtained.

In the various embodiments described above, the polishing pad 2018 maybe made of foamed urethane, or may be a non-woven-type or suede-typepolishing cloth. A fixed abrasive comprising abrasive particles fixedtogether by a binder such as epoxy may also be employed.

In all the above embodiments, the measurement fluid is preferably afluid having a high degree of cleanness and purity, so that a surface tobe measured (surface to be irradiated) of the substrate 2020, thelight-emitting optical fiber 2070, the light-receiving optical fiber2072, the supply passage 2042, and the discharge passage 2044 can becleaned effectively. The measurement fluid may be filtered by a filterdisposed in the fluid passage.

Although the preferred embodiments of the present invention have beendescribed above, the embodiments may be modified by those skilled in theart within the scope of the present invention.

According to the present invention, since the solvent of the slurry issupplied as the measurement fluid, even if the measurement fluid flowsout onto the polishing table and is mixed with the slurry, the influencethat the diluted slurry has on the polishing capability can be reduced.Thus, the influence that the measurement fluid has on the polishingcapability is reduced while maintaining the measuring capability.

Further, according to the present invention, since the highly viscousfluid is supplied as the measurement fluid, the diffusion of the slurryflowing into the measuring area can be reduced. Therefore, the influencethat the slurry has on film measurement can be reduced, thus increasingthe measuring capability. Since the amount of the measurement fluid thatflows out can be reduced, the influence that the measurement fluid hason the polishing capability is reduced while maintaining the measuringcapability.

Furthermore, according to the present invention, since the gas is usedas the measurement fluid, the slurry can efficiently be removed from themeasuring area, and hence the excellent measuring capability can beobtained. Even if the gas flows out, the slurry is not diluted.Therefore, the influence that the measurement fluid has on the polishingcapability can be reduced. Accordingly, the influence that themeasurement fluid has on the polishing capability can be reduced whilemaintaining the measuring capability.

1. A substrate polishing apparatus comprising: a polishing table; apolishing pad mounted on said polishing table for polishing asemiconductor substrate, said polishing pad having a through hole formedtherein; a light emission and reception device having an emitter foremitting measurement light through said through hole formed in saidpolishing pad to the semiconductor substrate and a receiver forreceiving reflected light from the semiconductor substrate so as tomeasure a film on the semiconductor substrate, said light emission andreception device being disposed in said polishing table; a supplypassage for supplying a fluid to a path of the measurement light so asto produce a flow of the fluid from said light emission and receptiondevice to the semiconductor substrate; and a discharge passage fordischarging the fluid in the path of the measurement light, saiddischarge passage being provided in said polishing table and having afluid connection with said supply passage, wherein said supply passagehas an outlet portion, and a portion of said emitter and a portion ofsaid receiver are located within said outlet portion.
 2. A substratepolishing apparatus according to claim 1, wherein said outlet portion isdetachably mounted on said polishing table and comprises a pipe unitwhich has a pipe piece.
 3. A substrate polishing apparatus according toclaim 1, wherein said emitter comprises a light-emitting optical fiber.4. A substrate polishing apparatus according to claim 1, wherein saidreceiver comprises a light-receiving optical fiber.
 5. A substratepolishing apparatus according to claim 1, wherein the fluid comprisespure water.
 6. A polishing apparatus according to claim 1, furthercomprising a pump connected to said discharge passage for compulsorilydischarging the fluid in the path of the measurement light.
 7. Apolishing apparatus according to claim 1, wherein said supply passagehas a nonreflective inner surface.
 8. A polishing apparatus according toclaim 1, further comprising an auxiliary supply passage for supplying afluid, said auxiliary supply passage being positioned at the forward ofsaid supply passage in a rotational direction of said polishing table.9. A polishing apparatus comprising: a polishing table having apolishing pad for polishing a workpiece, said polishing pad having ahole; an optical measurement device disposed in said polishing tablehaving an emitter for emitting measurement light to the workpiecethrough said hole and a receiver for receiving reflected light from theworkpiece so as to measure a film on the workpiece; a supply passagedisposed in said polishing table for supplying a fluid to a path of themeasurement light so as to produce a flow of the fluid tom said opticalmeasurement device to the workpiece; and a discharge passage fordischarging the fluid in the path of the measurement light, saiddischarge passage being provided in said polishing table and having afluid connection with said supply passage, wherein said supply passagehas an outlet portion, and a portion of said emitter and a portion ofsaid receiver are located within said outlet portion.
 10. A polishingapparatus according to claim 9, wherein said outlet portion isdetachably mounted on said polishing table and comprises a pipe unitwhich has a pipe piece.
 11. A polishing apparatus according to claim 9,wherein said emitter comprises a light-emitting optical fiber.
 12. Apolishing apparatus according to claim 9, wherein said receivercomprises a light-receiving optical fiber.
 13. A polishing apparatusaccording to claim 9, wherein the fluid comprises pure water.
 14. Apolishing apparatus according to claim 9, further comprising a pumpconnected to said discharge passage for compulsorily discharging thefluid in the path of the measurement light.
 15. A polishing apparatusaccording to claim 9, wherein the supply passage has a nonreflectiveinner surface.
 16. A polishing apparatus according to claim 9, farthercomprising an auxiliary supply passage for supplying a fluid, saidauxiliary supply passage being positioned at the forward of said supplypassage in a rotational direction of said polishing table.
 17. Asubstrate polishing apparatus comprising: a polishing table having apolishing pad thereon for polishing a semiconductor substrate; a lightemission and reception device for emitting measurement light through anopening formed in said polishing pad to the semiconductor substrate andreceiving reflected light from the semiconductor substrate so as tomeasure a film on the semiconductor substrate; a supply passage forsupplying a fluid to a path of the measurement light; and a protectioncover to be mounted on said polishing table, said protection cover beingfor covering said light emission and reception device, wherein saidprotection cover is mounted on said polishing table when said polishingpad is replaced and then detached from said polishing table beforepolishing.
 18. A substrate polishing apparatus according to claim 17,wherein said protection cover is configured to cover said supplypassage.
 19. A protection cover detachably mounted on a polishing tablehaving a light emission and reception device for emitting measurementlight through an opening formed in said polishing table to a substrateand receiving reflected light from the substrate so as to measure a filmon the substrate, said protection cover comprising: an outer surface tobe received by said opening; and a lower surface for covering saidopening so as to protect said light emission and reception device,wherein said protection cover is mounted on said polishing table whensaid polishing pad is replaced and then detached from said polishingtable before polishing.
 20. A protection cover according to claim 19,wherein said protection cover covers a supply passage provided in saidopening, said supply passage supplying a fluid to a path of themeasurement light.
 21. A protection cover according to claim 19, furthercomprising: an O-ring provided between said outer surface of saidprotection cover and an inner surface of said opening.
 22. A protectioncover according to claim 19, wherein said protection cover is fixed tosaid polishing table by bolts.